Materials Science

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New submissions for Tue, 16 Apr 24

[1]  arXiv:2404.08649 [pdf, ps, other]

Title: Note: Applying the Brillouin Zone and Band Gap Leveraging AB Initio Calculation for Digital Well-Being: In-Depth Analysis of Band Structures in Information Spaces Insights from Solid-State Physics

Authors: Yasuko Kawahata

Comments: AB Initio Calculation, First Brillouin Zone, Band Gap Theory, Reciprocal Lattice Vectors , Information Dissemination, Quantum Mechanics in Digital Media, Theoretical Framework for Digital Health, Influence Threshold in Information Spread

Subjects: Materials Science (cond-mat.mtrl-sci); Applied Physics (physics.app-ph)

The efforts of this Note are aimed at understanding various phenomena in digital space that are incomplete and difficult to define, and to translate them into language from research fields that are based on existing large-scale experimental data. Information diffusion and user behavior patterns in digital space are often hard to intuitively capture, and the principles and mechanisms behind them are difficult to articulate. To address this challenge, we have drawn on first-principles methods in physics, particularly solid state physics. This approach is known to be effective in analyzing the behavior of real physical materials at the atomic level and in understanding the electronic properties and bonding structures of materials. We have attempted to apply physical concepts based on first-principles calculations, in particular concepts such as first Brillouin zones, band gaps, and reciprocal lattice vectors, to digital space as a metaphor. This theoretical framework allows us to quantitatively and logically infer the behavior and trends of incomplete and ambiguous digital data and phenomena. For example, the "first Brillouin zone" of information in digital media indicates the potential sphere of influence of that information, and the band gap defines the threshold of influence for the information to be widely accepted. In addition, the reciprocal lattice vector serves as a boundary that indicates the limits of information characteristics and is an indicator of the degree to which a particular piece of information resonates with users. With this theoretical supplement, our research goes beyond the mere analysis of phenomena in the digital space and provides new methods for understanding and predicting the behavior of imperfect data and uncertain digital media.

[2]  arXiv:2404.08650 [pdf, other]

Title: QSPR Analysis with Curvilinear Regression Modeling and Temperature-based Topological Indices

Authors: H.M.Nagesh

Subjects: Materials Science (cond-mat.mtrl-sci); Chemical Physics (physics.chem-ph)

Establishing quantitative correlations between various molecular properties and chemical structures is of great technological importance for environmental and medical aspects. These approaches are referred to as Quantitative Structure-Property Relationships (QSPR), which relate the physicochemical or thermodynamic properties of compounds to their structures. The main goal of QSPR studies is to find a mathematical relationship between the property of interest and several molecular descriptors derived from the structure of the molecule. Topological indices are the molecular descriptors that characterize the formation of chemical compounds and predict certain physicochemical properties. In this study, the QSPR models are designed using certain temperature-based topological indices such as the sum connectivity temperature index, product connectivity temperature index, F-temperature index, and symmetric division temperature index to predict the thermodynamic properties, such as enthalpies of formation ($\Delta H^{0}_{f}$ \hspace{1mm} liquid), enthalpies of combustion ($\Delta H^{0}_{C}$ \hspace{1mm} liquid), and enthalpies of vaporization ($\Delta H^{0}_{vap}$ \hspace{1mm} gas) of monocarboxylic acids ($C_2H_{4}O_{2}$ - $C_{20}H_{40}O_{2}$). The relationship analysis between thermodynamic properties and topological indices is done using linear, quadratic, and cubic equations of a curvilinear regression model. These regression models are then compared.

[3]  arXiv:2404.08651 [pdf, other]

Title: Analysis of growth of silicon thin films on textured and non-textured surface

Authors: S. M. Iftiquar, S. N. Riaz, S. Mahapatra

Comments: 14 papes, 7 figs

Subjects: Materials Science (cond-mat.mtrl-sci); Applied Physics (physics.app-ph); Optics (physics.optics)

Hydrogenated amorphous silicon alloy films are generally deposited by radio frequency plasma enhanced chemical vapor deposition (RF PECVD) technique on various types of substrates. Generally it is assumed that film quality remains unchanged when deposited on textured or non-textured substrates. Here we analyzed the difference in growth of thin film silicon layers when deposited in a textured and a non-textured surface. In this investigation characteristics of two solar cells were compared, where one cell was prepared on a textured surface ( Cell-A) while the other prepared on a non-textured surface (Cell-B). Defect analysis of the devices were carried out by simulation and device modeling. It shows that the intrinsic film deposited on a textured surface was more defective ($2.4\times 10^{17}$ cm$^{-3}$) than that deposited on a flat surface ($3.2\times 10^{16}$ cm$^{-3}$). Although the primary differences in these two cells were thickness of the active layer and nature of surface texturing, the simulation results show that thin film deposited on a textured surface may acquire an increased defect density than that deposited on a flat surface. Lower effective flux density of $SiH_{3}$ precursors on the textured surface can be one of the reasons for higher defect density in the film deposited on textured surface. An Improved light coupling can be achieved by using a thinner doped window layer. By changing the thickness from 15 nm to 3 nm, the short circuit current density increased from 16.4 mA/cm$^{2}$ to 20.96 mA/cm$^{2}$ and efficiency increased from $9.4\%$ to $12.32\%$.

[4]  arXiv:2404.08653 [pdf, other]

Title: Machine-Learning Based Selection and Synthesis of Candidate Metal-Insulator Transition Metal Oxides

Authors: Alexandru B. Georgescu, Peiwen Ren, Christopher Karpovich, Elsa Olivetti, James M. Rondinelli

Subjects: Materials Science (cond-mat.mtrl-sci); Strongly Correlated Electrons (cond-mat.str-el)

The discovery of materials that exhibit a metal-insulator transition (MIT) is key to the development of multiple types of novel efficient microelectronic and optoelectronic devices. However, identifying MIT materials is challenging due to a combination of high computational cost of electronic structure calculations needed to understand their mechanism, the mechanisms' complexity, and the labor-intensive experimental validation process. To that end, we use a machine learning classification model to rapidly screen a high-throughput crystal structure database to identify candidate compounds exhibiting thermally-driven MITs. We focus on three candidate oxides, Ca$_2$Fe$_3$O$_8$, CaCo$_2$O$_4$, and CaMn$_2$O$_4$, and identify their MIT mechanism using high-fidelity density functional theory calculations. Then, we provide a probabilistic estimate of which synthesis reactions may lead to their realization. Our approach couples physics-informed machine learning, density functional theory calculations, and machine learning-suggested synthesis to reduce the time to discovery and synthesis of new technologically relevant materials.

[5]  arXiv:2404.08657 [pdf, other]

Title: Advancing Extrapolative Predictions of Material Properties through Learning to Learn

Authors: Kohei Noda, Araki Wakiuchi, Yoshihiro Hayashi, Ryo Yoshida

Comments: 26 pages, 7 figures

Subjects: Materials Science (cond-mat.mtrl-sci); Soft Condensed Matter (cond-mat.soft); Machine Learning (cs.LG)

Recent advancements in machine learning have showcased its potential to significantly accelerate the discovery of new materials. Central to this progress is the development of rapidly computable property predictors, enabling the identification of novel materials with desired properties from vast material spaces. However, the limited availability of data resources poses a significant challenge in data-driven materials research, particularly hindering the exploration of innovative materials beyond the boundaries of existing data. While machine learning predictors are inherently interpolative, establishing a general methodology to create an extrapolative predictor remains a fundamental challenge, limiting the search for innovative materials beyond existing data boundaries. In this study, we leverage an attention-based architecture of neural networks and meta-learning algorithms to acquire extrapolative generalization capability. The meta-learners, experienced repeatedly with arbitrarily generated extrapolative tasks, can acquire outstanding generalization capability in unexplored material spaces. Through the tasks of predicting the physical properties of polymeric materials and hybrid organic--inorganic perovskites, we highlight the potential of such extrapolatively trained models, particularly with their ability to rapidly adapt to unseen material domains in transfer learning scenarios.

[6]  arXiv:2404.08658 [pdf, other]

Title: Coupling Phase Field Crystal and Field Dislocation Mechanics for a consistent description of dislocation structure and elasticity

Authors: Manas Vijay Upadhyay, Jorge Viñals

Subjects: Materials Science (cond-mat.mtrl-sci)

This work addresses differences in predicted elastic fields created by dislocations either by the Phase Field Crystal (PFC) model, or by static Field Dislocation Mechanics (FDM). The PFC order parameter describes the topological content of the lattice, but it fails to correctly capture the elastic distortion. In contrast, static FDM correctly captures the latter but requires input about defect cores. The case of a dislocation dipole in two dimensional, isotropic, elastic medium is studied, and a weak coupling is introduced between the two models. The PFC model produces compact and stable dislocation cores, free of any singularity, i.e., diffuse. The PFC predicted dislocation density field (a measure of the topological defect content) is used as the source (input) for the static FDM problem. This coupling allows a critical analysis of the relative role played by configurational (from PFC) and elastic (from static FDM) fields in the theory, and of the consequences of the lack of elastic relaxation in the diffusive evolution of the PFC order parameter.

[7]  arXiv:2404.08783 [pdf, ps, other]

Title: Stabilizing perpendicular magnetic anisotropy with strong exchange bias in PtMn/Co by magneto-ionics

Authors: Beatrice Bednarz, Maria-Andromachi Syskaki, Rohit Pachat, Leon Prädel, Martin Wortmann, Timo Kuschel, Shimpei Ono, Mathias Kläui, Liza Herrera Diez, Gerhard Jakob

Comments: main manuscript and supplementary material

Subjects: Materials Science (cond-mat.mtrl-sci); Mesoscale and Nanoscale Physics (cond-mat.mes-hall)

Electric field control of magnetic properties offers a broad and promising toolbox for enabling ultra-low power electronics. A key challenge with high technological relevance is to master the interplay between the magnetic anisotropy of a ferromagnet and the exchange coupling to an adjacent antiferromagnet. Here, we demonstrate that magneto-ionic gating can be used to achieve a very stable out-of-plane (OOP) oriented magnetization with strong exchange bias in samples with as-deposited preferred in-plane (IP) magnetization. We show that the perpendicular interfacial anisotropy can be increased by a factor of 2.2 in the stack Ta/Pt/PtMn/Co/HfO2 by applying -2.5 V gate voltage over 3 nm HfO2, causing a reorientation of the magnetization from IP into OOP with a strong OOP exchange bias of more than 50 mT. Comparing two thicknesses of PtMn, we identify a notable trade-off: while thicker PtMn yields a significantly larger exchange bias, it also results in a slower response to ionic liquid gating. These results pave the way for post-deposition electrical tailoring of magnetic anisotropy and exchange bias in samples requiring significant exchange bias.

[8]  arXiv:2404.08872 [pdf, ps, other]

Title: Enhanced Hydrogen Evolution Activity of MOS$_2$-rGO Composite Synthesized via Hydrothermal Technique

Authors: Abhishek Sebastian, Pragna R

Comments: This research is an excerpt from the report of TARP (Technical Answers for Real-World Problems)

Subjects: Materials Science (cond-mat.mtrl-sci); Artificial Intelligence (cs.AI)

Hydrogen evolution reaction (HER) has emerged as a promising technique for the production of clean and sustainable energy. In recent years, researchers have been exploring various materials for efficient HER activity. In this study, we report the synthesis of two different materials, namely MOS$_2$ and MoS$_2$-rGO, through a hydrothermal technique. X-ray diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy, and Raman spectroscopy were used to characterize the materials. XRD analysis revealed the formation of hexagonal MOS$_2$ with a high degree of crystallinity. FTIR analysis confirmed the presence of Mo-S bonds, while Raman spectroscopy provided evidence for the formation of MOS$_2$.To evaluate the HER activity of the materials, linear sweep voltammetry (LSV) was performed. The results showed that MOS$_2$ and MOS$_2$-rGO had good HER activity with low onset potentials and high current densities. The MOS$_2$-rGO material showed improved HER activity compared to MOS$_2$, indicating the potential of graphene oxide as a co-catalyst to enhance the performance of MOS$_2$.

[9]  arXiv:2404.08875 [pdf, ps, other]

Title: Layer-by-layer connection for large area single crystal boron nitride multilayer films

Authors: Hui Shi, Mingyuan Wang, Hongying Chen, Adrien Rousseau, Junpeng Shu, Ming Tian, Ruowang Chen, Juliette Plo, Pierre Valvin, Bernard Gil, Jiajie Qi, Qinghe Wang, Kaihui Liu, Mingliang Zhang, Guillaume Cassabois, Di Wu, Neng Wan

Subjects: Materials Science (cond-mat.mtrl-sci)

Boron nitride (BN) is today considered as one of the most promising materials for many novel applications including bright single photon emission, deep UV opto-electronics, small sized solid-state neutron detector, and high-performance two-dimensional materials, etc. Despite the recent successful fabrication of large-area BN single-crystals (typically <= 5 atomic layers), the scalable growth of thicker single-crystalline BN films still constitutes a great challenge. In this work, we demonstrate an approach to grow large-area multilayer single-crystal BN films by chemical vapor deposition on face-centered cubic Fe-Ni (111) single crystal alloy thin films with different stoichiometric phases. We show that the BN growth is greatly tunable and improved by increasing the Fe content in single-crystal Fe-Ni (111). The formation of pyramid-shaped multilayer BN domains with aligned orientation enables a continuous connection following a layer-by-layer, 'first-meet-first-connect', mosaic stitching mechanism. By means of selected area electron diffraction, micro-photoluminescence spectroscopy in the deep UV and high-resolution transmission electron microscopy, the layer-by-layer connection mechanism is unambiguously evidenced, and the stacking order has been verified to occur as unidirectional AB and ABC stackings, i.e., in the Bernal and rhombohedral BN phase.

[10]  arXiv:2404.08924 [pdf, ps, other]

Title: Stable phases of freestanding monolayer TiO$_2$: The emergence of out-of-plane ferroelectricity

Authors: Xiangtian Bu, Haitao Liu, Yuanchang Li

Comments: accepted by PRB

Subjects: Materials Science (cond-mat.mtrl-sci); Mesoscale and Nanoscale Physics (cond-mat.mes-hall)

Despite being successfully synthesized [Zhang $et$ $al.$, Nat. Mater. \textbf{20}, 1073 (2021)], the monolayer structure of stable hexagonal TiO$_2$ is unknown, and it is not even clear whether it can exist in a freestanding form. Through first-principles calculations, we have identified two previously uncharted stable structures, namely, distorted 1$\times$$\sqrt{3}$ 1T-TiO$_2$ and $\sqrt{3}$$\times$$\sqrt{3}$ 1T-TiO$_2$, both of which are energetically more favourable than commonly adopted 1H and 1T phases. Here structural distortions are characterized by the out-of-plane shifts of Ti atoms due to the pseudo-Jahn-Teller interactions, which break one and all two inversion symmetries of 1T configuration. As a consequence, the 1$\times$$\sqrt{3}$ 1T remains centrosymmetric while the $\sqrt{3}$$\times$$\sqrt{3}$ 1T exhibits out-of-plane ferroelectricity. Electronic structure calculations show that both two are wide-bandgap semiconductors with bandgaps larger than their bulk counterparts. Our study not only deepens the understanding of structural instability in wide-gap semiconductors but also adds a new member to the rare family of two-dimensional out-of-plane ferroelectrics.

[11]  arXiv:2404.08988 [pdf, ps, other]

Title: Ferroelectrovalley in Two-Dimensional Multiferroic Lattices

Authors: Jiangyu Zhao, Yangyang Feng, Ying Dai, Baibiao Huang, Yandong Ma

Subjects: Materials Science (cond-mat.mtrl-sci)

Engineering valley index is essential and highly sought for valley physics, but currently it is exclusively based on the paradigm of the challenging ferrovalley with spin-orientation reversal under magnetic field. Here, an alternative strategy, i.e., the so-called ferroelectrovalley, is proposed to tackle the insurmountable spin-orientation reversal, which reveres valley index with the feasible ferroelectricity. Using symmetry arguments and tight-binding model, the C_2 rotation is unveiled to be able to take the place of time reversal for operating valley index in two-dimensional multiferroic kagome lattices, which enables the ferroelectricity-engineered valley index, thereby generating the concept of ferroelectrovalley. Based on first-principles calculations, this concept is further demonstrated in the breathing kagome lattice of single-layer Ti3Br8, wherein ferroelectricity couples the breathing process. These findings open a new direction for valleytronics and two-dimensional materials research.

[12]  arXiv:2404.09008 [pdf, ps, other]

Title: Combinatorial Printing of Functionally Graded Solid-State Electrolyte for High-Voltage Lithium Metal Batteries

Authors: Qiang Jiang, Stephanie Atampugre, Yipu Du, Lingyu Yang, Jennifer L. Schaefer, Yanliang Zhang

Subjects: Materials Science (cond-mat.mtrl-sci)

Heterogeneous multilayered solid-state electrolyte (HMSSE) has been widely explored for their broadened working voltage range and compatibility with electrodes. However, due to the limitations of traditional manufacturing methods such as casting, the interface between electrolyte layers in HMSSE can decrease the ionic conductivity severely. Here, a novel combinatory aerosol jet printing (CAJP) is introduced to fabricate functionally graded solid-state electrolyte (FGSSE) without sharp interface. Owing to the unique ability of CAJP (in-situ mixing and instantaneous tuning of the mixing ratio), FGSSE with smooth microscale compositional gradation is achieved. Electrochemical tests show that FGSSE has excellent oxidative stability exceeding 5.5 V and improved conductivity (>7 times of an analogous HMSSE). By decoupling the total resistance, we show that the resistance from the electrolyte/electrolyte interface of HMSSE is 5.7 times of the total resistance of FGSSE. The Li/FGSSE/NCM622 cell can be stably run for more than 200 cycles along with improved rate performance.

[13]  arXiv:2404.09038 [pdf, ps, other]

Title: Solution-Processed Inks with Fillers of NbS$_3$ Quasi-One-Dimensional Charge-Density-Wave Material

Authors: Tekwam Geremew, Maedeh Taheri, Nicholas Sesing, Subhajit Ghosh, Fariborz Kargar, Tina T. Salguero, Alexander A. Balandin

Comments: 25 pages; 5 figures

Subjects: Materials Science (cond-mat.mtrl-sci); Mesoscale and Nanoscale Physics (cond-mat.mes-hall)

We report on the solution processing and testing of electronic ink comprised of quasi-one-dimensional NbS$_3$ charge-density-wave fillers. The ink was prepared by liquid-phase exfoliation of NbS$_3$ crystals into high-aspect ratio quasi-1D fillers dispersed in a mixture of isopropyl alcohol and ethylene glycol solution. The results of the electrical measurements of two-terminal electronic test structures printed on silicon substrates reveal resistance anomalies in the temperature range of ~330 K to 370 K. It was found that the changes in the temperature-dependent resistive characteristics of the test structures originate from the charge-density-wave phase transition of individual NbS$_3$ fillers. The latter confirms that the exfoliated NbS$_3$ fillers preserve their intrinsic charge-density-wave quantum condensate states and can undergo phase transitions above room temperature even after chemical exfoliation processes and printing. These results are important for developing "quantum inks" with charge-density-wave fillers for the increased functionality of future solution-processed electronics.

[14]  arXiv:2404.09148 [pdf, ps, other]

Title: Tuning the thermal conductivity of Si membrane using nanopillars: from crystalline to amorphous pillars

Authors: Lina Yang, Yixin Xu, Xianheng Wang, Yanguang Zhou

Subjects: Materials Science (cond-mat.mtrl-sci)

Tuning thermal transport in nanostructures is essential for many applications, such as thermal management and thermoelectrics. Nanophononic metamaterials (NPM) have shown great potential for reducing thermal conductivity by introducing local resonant hybridization. In this work, the thermal conductivity of NPM with crystalline Si (c-Si) pillar, crystalline Ge (c-Ge) pillar and amorphous Si (a-Si) pillar are systematically investigated by molecular dynamics method. The analyses of phonon dispersion and spectral energy density show that phonon dispersions of Si membrane are flattened due to local resonant hybridization induced by both crystalline and amorphous pillar. In addition, a-Si pillar can cause larger reduction of thermal conductivity compared with c-Si pillar. Specifically, when increasing the atomic mass of atoms in pillars, the thermal conductivity of NPMs with crystalline pillar is increased because of the weakened phonon hybridization, however, the thermal conductivity of NPMs with amorphous pillar is almost unchanged, which indicates that the phonon transports are mainly affected by the scatterings at the interface between amorphous pillar and Si membrane. The results of this work can provide meaningful insights on controlling thermal transport in NPMs by choosing the materials and atomic mass of pillars for specific applications.

[15]  arXiv:2404.09325 [pdf, other]

Title: Exceptionally High Two-Photon Absorption in Diazaacene-Bithiophene Derivatives: A Combined Experimental and Theoretical Approach

Authors: Gabriel Sauter, Antonia Papapostolou, Audrey Pollien, Sergius Boschmann, Kathleen Fuchs, Jan Freudenberg, Uwe H. F. Bunz, Andreas Dreuw, Petra Tegeder

Comments: 26 pages; 12 figures

Subjects: Materials Science (cond-mat.mtrl-sci)

This study delves into the enhancement of two-photon absorption (2PA) properties in diazaacene-bithiophene derivatives through a synergistic approach combining theoretical analysis and experimental validation. By investigating the structural modifications and their impact on 2PA cross sections, we identify key factors that significantly influence the 2PA efficiency. For all molecular systems studied, our state-of-the-art quantum chemical calculations show a very high involvement of the first excited singlet state (S1) in the 2PA processes into higher excited states, even if this state itself has only a small 2PA cross section for symmetry reasons. Consequently, both the oscillator strength of S1 and the transition dipole moments between S1 and other excited states are of importance, underscoring the role of electronic polarizability in facilitating effective two-photon interactions. The investigated compounds exhibit large 2PA cross sections over a wide near-infrared spectral range reaching giant values of 42000 GM. The introduction of diazine and diazaacene moieties into bithiophene derivatives not only induces charge transfer but also opens up pathways for the creation of materials with tailored nonlinear optical responses, suggesting potential applications in nonlinear optics.

[16]  arXiv:2404.09340 [pdf, ps, other]

Title: Nitrogen-monovacancy (VN) Hexagonal Boron Nitride 2D Monolayer Material as an Efficient Electrocatalyst for CO2 Reduction Reaction

Authors: Lokesh Yadav, Srimanta Pakhira

Comments: 33 pages

Subjects: Materials Science (cond-mat.mtrl-sci)

The conversion of waste carbon dioxide (CO2) gas into valuable products and fuels through an electrocatalytic CO2 reduction reaction (CO2RR) is a promising approach. The sluggish kinetics of the CO2RR require the development of novel strategies for electrocatalyst design. Two-dimensional (2D) materials emerge as promising candidates for CO2RR due to their distinctive electronic and structural properties. This study follows the first principles based DFT-D method to examine the electrocatalytic competences of the defective two-dimensional boron nitride monolayer (d-BN) material towards CO2RR. Introducing a particular defect with nitrogen vacancies in the 2D single layer pristine hexagonal boron nitride (VN_d-BN) can efficiently activate the CO2 molecules for hydrogenation by reducing the electronic band gap of the pristine hBN from 6.23 eV to 3.0 eV. Therefore, VN_d-BN material can act as a large band gap semiconductor. Our findings demonstrate that the defective regions in the 2D monolayer VN_d-BN serve as active sites (Boron) for both the adsorption and activation of CO2. The subsequent hydrogenation steps occur sequentially once the CO2 molecule is adsorbed on the catalytic surface. Our results indicate that the OCHO* path is the most favorable for CH4 production. Hence, the 2D monolayer VN_d-BN material holds a great promise as a cost-effective catalyst for CO2RR, and it presents a viable alternative to expensive platinum (Pt) catalysts.

[17]  arXiv:2404.09345 [pdf, other]

Title: Blue quantum emitter in hexagonal boron nitride and carbon chain tetramer: proposition of identification

Authors: Marek Maciaszek, Lukas Razinkovas

Comments: 7 pages, 3 figures

Subjects: Materials Science (cond-mat.mtrl-sci)

Single photon emitters in hexagonal boron nitride offer a gateway to the future of quantum technologies, yet their identification remains challenging and subject to ongoing debate. We demonstrate through ab initio calculations that the optical properties of a carbon chain tetramer are in excellent agreement with the characteristics of a blue quantum emitter in hexagonal boron nitride emitting at 435 nm. Its calculated zero-phonon line energy (2.77 eV) and radiative lifetime (1.6 ns) perfectly align with experimental observations. The relatively weak electron--phonon coupling (Huang-Rhys factor of 1.5) indicates intense emission at the zero-phonon line. Despite the absence of an inversion center in the carbon tetramer, we demonstrate that it exhibits a negligible linear Stark effect, consistent with experimental findings. Additionally, our hypothesis explains the experimental observation that the formation of blue emitters is only possible in samples containing numerous ultraviolet emitters, which are likely identical to carbon dimers.

[18]  arXiv:2404.09394 [pdf, ps, other]

Title: Fluorite-type materials in the monolayer limit

Authors: Shota Ono, Ravinder Pawar

Comments: 8 pages, 4 figures

Subjects: Materials Science (cond-mat.mtrl-sci)

The 2H, 1T, and their distorted structures are known as prototype structures of $AB_2$ monolayers. Here, we study a puckered structure that is truncated from the (110) surface of fluorite-type materials. 53 fluorite-type materials are investigated based on first-principles approach. The formation energy calculations indicate that seven systems form the puckered structure in the monolayer limit, while other systems form either 1T, 2H, or distorted 1T structures. The puckered structures of PbF$_2$, PRh$_2$, and Ga$_2$Au exhibit negative Poisson's ratio (NPR) in the out-of-plane direction. An analytical model for the NPR is derived. The surface energy calculations predict the appearance of NPR.

[19]  arXiv:2404.09457 [pdf, ps, other]

Title: High-performance magnesium/sodium hybrid ion battery based on sodium vanadate oxide for reversible storage of Na+ and Mg2+

Authors: Xiaoke Wang, Titi Li, Xixi Zhang, Yaxin Wang, Hongfei Li, Hai-Feng Li, Gang Zhao, Cuiping Han

Subjects: Materials Science (cond-mat.mtrl-sci); Chemical Physics (physics.chem-ph)

Magnesium ion batteries (MIBs) are a potential field for the energy storage of the future but are restricted by insufficient rate capability and rapid capacity degradation. Magnesium-sodium hybrid ion batteries (MSHBs) are an effective way to address these problems. Here, we report a new type of MSHBs that use layered sodium vanadate ((Na, Mn)V8O20 5H2O, Mn-NVO) cathodes coupled with an organic 3,4,9,10-perylenetetracarboxylic diimide (PTCDI) anode in Mg2+/Na+ hybrid electrolytes. During electrochemical cycling, Mg2+ and Na+ co-participate in the cathode reactions, and the introduction of Na+ promotes the structural stability of the Mn-NVO cathode, as cleared by several ex-situ characterizations. Consequently, the Mn-NVO cathode presents great specific capacity (249.9 mAh g-1 at 300 mA g-1) and cycling (1500 cycles at 1500 mA g-1) in the Mg2+/Na+ hybrid electrolytes. Besides, full battery displays long lifespan with 10,000 cycles at 1000 mA g-1. The rate performance and cycling stability of MSHBs have been improved by an economical and scalable method, and the mechanism for these improvements was discussed.

[20]  arXiv:2404.09543 [pdf, ps, other]

Title: Van der Waals epitaxy of Weyl-semimetal Td-WTe$_2$

Authors: Alexandre Llopez (CINaM), Frédéric Leroy (CINaM), Calvin Tagne-Kaegom (IJL), Boris Croes (CINaM, IPCMS), Adrien Michon (CRHEA), Chiara Mastropasqua (CRHEA), Mohamed Al Khalfioui (CRHEA), Stefano Curiotto (CINaM), Pierre Müller (CINaM), Andrés Saùl (CINaM), Bertrand Kierren (IJL), Geoffroy Kremer (IJL), Patrick Le Fèvre (SSOLEIL, IPR), François Bertran (SSOLEIL), Yannick Fagot-Revurat (IJL), Fabien Cheynis (CINaM, AMU)

Comments: ACS Applied Materials and Interfaces, 2024

Subjects: Materials Science (cond-mat.mtrl-sci)

Epitaxial growth of WTe$_2$ offers significant advantages, including the production of high-qualityfilms, possible long range in-plane ordering and precise control over layer thicknesses. However,the mean island size of WTe$_2$ grown by molecular beam epitaxy (MBE) in litterature is only a fewtens of nanometers, which is not suitable for an implementation of devices at large lateral scales.Here we report the growth of Td-WTe$_2$ ultrathin films by MBE on monolayer (ML) graphenereaching a mean flake size of $\cong$110nm, which is, on overage, more than three time larger thanprevious results. WTe$_2$ films thicker than 5nm have been successfully synthesized and exhibit theexpected Td-phase atomic structure. We rationalize epitaxial growth of Td-WTe$_2$ and propose asimple model to estimate the mean flake size as a function of growth parameters that can be appliedto other transition metal dichalcogenides (TMDCs). Based on nucleation theory and Kolmogorov-Johnson-Meh-Avrami (KJMA) equation, our analytical model supports experimental data showinga critical coverage of 0.13ML above which WTe$_2$ nucleation becomes negligible. The quality ofmonolayer WTe$_2$ films is demonstrated from electronic band structure analysis using angle-resolved photoemission spectroscopy (ARPES) in agreement with first-principle calculationsperformed on free-standing WTe$_2$ and previous reports.

[21]  arXiv:2404.09569 [pdf, ps, other]

Title: Surprising pressure-induced magnetic transformations from Helimagnetic order to Antiferromagnetic state in NiI2

Authors: Qiye Liu, Wenjie Su, Yue Gu, Xi Zhang, Xiuquan Xia, Le Wang, Ke Xiao, Xiaodong Cui, Xiaolong Zou, Bin Xi, Jia-Wei Mei, Jun-Feng Dai

Subjects: Materials Science (cond-mat.mtrl-sci); Mesoscale and Nanoscale Physics (cond-mat.mes-hall)

Interlayer magnetic interactions play a pivotal role in determining the magnetic arrangement within van der Waals (vdW) magnets, and the remarkable tunability of these interactions through applied pressure further enhances their significance. Here, we investigate NiI2 flakes, a representative vdW magnet, under hydrostatic pressures up to 11 GPa. We reveal a notable increase in magnetic transition temperatures for both helimagnetic and antiferromagnetic states, and find that a reversible transition from helimagnetic to antiferromagnetic (AFM) phases at approximately 7 GPa challenges established theoretical and experimental expectations. While the increase in transition temperature aligns with pressure-enhanced overall exchange interaction strengths, we identify the significant role of the second-nearest neighbor interlayer interaction, which competes with intra-layer frustration and favors the AFM state as demonstrated in the Monte Carlo simulations. Experimental and simulated results converge on the existence of an intermediate helimagnetic ordered state in NiI2 before transitioning to the AFM state. These findings underscore the pivotal role of interlayer interactions in shaping the magnetic ground state, providing fresh perspectives for innovative applications in nanoscale magnetic device design.

[22]  arXiv:2404.09602 [pdf, other]

Title: Guidelines for accurate and efficient calculations of mobilities in two-dimensional materials

Authors: Jiaqi Zhou, Samuel Poncé, Jean-Christophe Charlier

Comments: 11 pages, 15 figures

Subjects: Materials Science (cond-mat.mtrl-sci); Computational Physics (physics.comp-ph)

Emerging two-dimensional (2D) materials bring unprecedented opportunities for electronic applications. The design of high-performance devices requires an accurate prediction of carrier mobility in 2D materials, which can be obtained using state-of-the-art $ab~initio$ calculations. However, various factors impact the computational accuracy, leading to contradictory estimations for the mobility. In this work, targeting accurate and efficient $ab~initio$ calculations, transport properties in III-V monolayers are reported using the Boltzmann transport equation, and the influences of pseudopotential, quadrupole correction, Berry connection, and spin-orbit coupling (SOC) on mobilities are systematically investigated. Our findings are as follows: (1) The inclusion of semi-core states in pseudopotentials is important to obtain accurate calculations. (2) The variations induced by dynamical quadrupole and Berry connection when treating long range fields can be respectively 40% and 10%. (3) The impact of SOC can reach up to 100% for materials with multi-peak bands. Importantly, although SOC notably modifies the electronic wavefunctions, it negligibly impacts the dynamical matrices and scattering potential variations. As a result, the combination of fully-relativistic electron calculation and scalar-relativistic phonon calculation can strike a good balance between accuracy and cost. This work compares computational methodologies, providing guidelines for accurate and efficient calculations of mobilities in 2D semiconductors.

[23]  arXiv:2404.09678 [pdf, ps, other]

Title: On the chemical potential and grand potential density of solids under non-hydrostatic stress

Authors: Michiel Sprik

Comments: 18 pages, no figures

Subjects: Materials Science (cond-mat.mtrl-sci)

Non-hydrostatic stress has a peculiar effect on the phase equilibrium between solids and liquids. This was already pointed out by Gibbs. Gibbs derived his formulation of the condition for liquid-solid coexistence applying a surface accretion process without imposing chemical equilibrium between liquid and solid. Adding particles to the bulk of a solid was not possible in his view at the time. Chemical potentials for solids were later introduced by material scientists. This required extending chemical and mechanical equilibrium with a third condition involving a relation between grand potential densities controlling the migration of the interface. These issues are investigated using a non-linear elastic continuum model (technically an open compressible neo-Hookean material) developed in a previous publication (M. Sprik, J. Chem. Phys. 155, (2021) 244701). In common with a liquid, the grand potential density of the model is equal to minus the mean pressure even if the stress is non-hydrostatic. Applying isothermal compression normal to a liquid-solid interface initially in hydrostatic equilibrium drives the system away from coexistence. We derive the Gibbs-Thomson correction to the pressure of the liquid required to restore phase equilibrium. We find that the coupling between chemical potential of the solid and shear stress is a purely non-linear effect.

[24]  arXiv:2404.09689 [pdf, ps, other]

Title: Strain-polarization coupling in the low-dimensional Van der Waals Ferrielectrics

Authors: Anna N. Morozovska, Hanna V. Shevliakova, Liubomyr M. Korolevych, Victoria Khist, Yulian M. Vysochanskii, Eugene A. Eliseev

Comments: 6 pages, 3 figures

Subjects: Materials Science (cond-mat.mtrl-sci); Mesoscale and Nanoscale Physics (cond-mat.mes-hall)

Using the Landau-Ginzburg-Devonshire phenomenological approach we explore the strain-polarization coupling in the low-dimensional van der Waals ferrielectrics. We evolve the analytical model of the piezoelectric susceptibility of the material in response to the periodic strain modulation, such as caused by a surface acoustic wave. Numerical calculations are performed for recently discovered and poorly studied ultrathin layers of the van der Waals ferrielectric CuInP2S6, which are very promising candidates for advanced nanoelectronics. We obtained that the temperature dependences of the dielectric and piezoelectric susceptibilities, and elastic compliance of the ultrathin CuInP2S6 layer have a sharp maximum at the temperature of CuInP2S6 paraelectric-ferrielectric phase transition near 320 K. The magnitudes of the dielectric and piezoelectric susceptibilities, and elastic compliance depend significantly on the modulation period of the surface acoustic wave. Obtained results explore the potential of ultrathin CuInP2S6 layers for application in piezoelectric and straintronic devices.

[25]  arXiv:2404.09739 [pdf, ps, other]

Title: Simulation of perovskite thin layer crystallization with varying evaporation rates

Authors: M. Majewski, S. Qiu, O. Ronsin, L. Lüer, V. M. Le Corre, T. Du, C. J. Brabec, H.-J. Egelhaaf, J. Harting

Comments: paper 10 pages, SI 26 pages

Subjects: Materials Science (cond-mat.mtrl-sci)

Perovskite solar cells (PSC) are promising potential competitors to established photovoltaic technologies due to their superior efficiency and low-cost solution processability. However, the limited understanding of the crystallization behaviour hinders the technological transition from lab-scale cells to modules. In this work, we perform Phase Field (PF) simulations of the doctor-bladed film formation to obtain mechanistic and morphological information that is experimentally challenging to access. PF simulations are validated extensively using in- and ex-situ experiments for different solvent evaporation rates. The well-known transition from a film with many pinholes, for a low evaporation rate, to a smooth film, for high evaporation rates, is recovered in simulation and experiment. From the simulation, the transition can be assigned to the change in the ratio of evaporation to crystallization rate because of two distinct mechanisms. Firstly, for larger evaporation rates, nuclei appear at higher concentrations, which favors nucleation as compared to growth. Secondly, the growth of the crystals is confined in a thinner film, which limits their vertical size. Both effects are expected to be valid independent of the specific chemistry of the chosen experimental system, as long as the evaporation time of the solvent is comparable to the crystallization time.

[26]  arXiv:2404.09906 [pdf, other]

Title: Photoluminescence of Femtosecond Laser-irradiated Silicon Carbide

Authors: Y. Abdedou, A. Fuchs, P. Fuchs, D. Herrmann, S. Weber, M. Schäfer, J. L'huillier, C. Becher, E. Neu

Comments: 7 pages, 6 figures

Subjects: Materials Science (cond-mat.mtrl-sci); Optics (physics.optics)

Silicon carbide (SiC) is the leading wide-bandgap semiconductor material, providing mature doping and device fabrication. Additionally, SiC hosts a multitude of optically active point defects (color centers), it is an excellent material for optical resonators due to its high refractive index and an outstanding material for mechanical resonators due to its high Q/f product. Moreover, epitaxial graphene layers can be grown as ultrathin electrodes and provide the potential to fine-tune color center resonances. These characteristics render SiC an ideal platform for experiments with single color centers towards quantum technologies including coupling color centers towards cooperative effects. A crucial step towards harnessing the full potential of the SiC platform includes technologies to create color centers with defined localization and density, e.g.\ to facilitate their coupling to nano-photonic structures and to observe cooperative effects. Here, silicon vacancy centers (V$_{Si}$) stand out as no impurity atom is needed and high-thermal budget annealing steps can be avoided. We characterize the effect of localized, femtosecond laser irradiation of SiC, investigating surface modifications and photoluminescence including Raman spectroscopy and optical lifetime measurements.

[27]  arXiv:2404.09913 [pdf, other]

Title: Fermi surface mediated enhancement of bulk photovoltaic effects in ZnGeP$_2$

Authors: Banasree Sadhukhan

Subjects: Materials Science (cond-mat.mtrl-sci)

Bulk photovoltaic effect is a non-linear response in noncentrosymmetric materials that converts light to a DC current. In this work, we investigate the optical linear and non-linear responses of the chalcopyrite semiconductor ZnGeP$_2$. We report the enhancement of bulk photovoltaics namely shift and circular photogalvanic (CPG) current conductivities due to intrinsic contribution of Fermi surface along the high symmetry $\Gamma-Z$ direction. We observe that the magnification of shift and CPG current conductivities around the incident photon energy $\sim 5$ eV are about 38\% and 81\% respectively in ZnGeP$_2$ due to shifting of Fermi level to 1.52 eV. To further verify our findings, we explore distribution of bulk Fermi surface states in both three dimensional Brillouin zone and surface Fermi surface distribution in the projected energy landscape using semi infinite slab geometry. Our study not only provides a deeper understanding of the roles of Fermi surface contribution on the bulk photovoltaic responses, but also suggests the ZnGeP$_2$ is an ideal candidate for optoelectronics.

[28]  arXiv:2404.09986 [pdf, ps, other]

Title: Thermal conversion of ultrathin nickel hydroxide for wide bandgap 2D nickel oxides

Authors: Lu Ping, Nicholas Russo, Zifan Wang, Ching-Hsiang Yao, Kevin E. Smith, Xi Ling

Subjects: Materials Science (cond-mat.mtrl-sci); Mesoscale and Nanoscale Physics (cond-mat.mes-hall)

Wide bandgap (WBG) semiconductors (Eg >2.0 eV) are integral to the advancement of next generation electronics, optoelectronics, and power industries, owing to their capability for high temperature operation, high breakdown voltage and efficient light emission. Enhanced power efficiency and functional performance can be attained through miniaturization, specifically via the integration of device fabrication into two-dimensional (2D) structure enabled by WBG 2D semiconductors. However, as an essential subgroup of WBG semiconductors, 2D transition metal oxides (TMOs) remain largely underexplored in terms of physical properties and applications in 2D opto-electronic devices, primarily due to the scarcity of sufficiently large 2D crystals. Thus, our goal is to develop synthesis pathways for 2D TMOs possessing large crystal domain (e.g. >10 nm), expanding the 2D TMOs family and providing insights for future engineering of 2D TMOs. Here, we demonstrate the synthesis of WBG 2D nickel oxide (NiO) (Eg > 2.7 eV) thermally converted from 2D nickel hydroxide (Ni(OH)2) with the lateral domain size larger than 10 um. Moreover, the conversion process is investigated using various microscopic techniques such as atomic force microscopy (AFM), Raman spectroscopy, transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS), providing significant insights on the morphology and structure variation under different oxidative conditions. The electronic structure of the converted NixOy is further investigated using multiple soft X-ray spectroscopies, such as X-ray absorption (XAS) and emission spectroscopies (XES).

Cross-lists for Tue, 16 Apr 24

[29]  arXiv:2404.08782 (cross-list from cond-mat.str-el) [pdf, other]

Title: Phase transitions of correlated systems from graph neural networks with quantum embedding techniques

Authors: Rishi Rao, Li Zhu

Comments: 7 pages, 4 figures

Subjects: Strongly Correlated Electrons (cond-mat.str-el); Materials Science (cond-mat.mtrl-sci); Computational Physics (physics.comp-ph)

Correlated systems represent a class of materials that are difficult to describe through traditional electronic structure methods. The computational demand to simulate the structural dynamics of such systems, with correlation effects considered, is substantial. Here, we investigate the structural dynamics of $f$- and $d$-electron correlated systems by integrating quantum embedding techniques with interatomic potentials derived from graph neural networks. For Cerium, a prototypical correlated $f$-electron system, we use Density Functional Theory with the Gutzwiller approximation to generate training data due to efficiency with which correlations effects are included for large multi-orbital systems. For Nickel Oxide, a prototypical correlated $d$-electron system, advancements in computational capabilities now permit the use of full Dynamical Mean Field Theory to obtain energies and forces. We train neural networks on this data to create a model of the potential energy surface, enabling rapid and effective exploration of structural dynamics. Utilizing these potentials, we delineate transition pathways between the $\alpha$, $\alpha'$, and $\alpha''$ phases of Cerium and predict the melting curve of Nickel Oxide. Our results demonstrate the potential of machine learning potentials to accelerate the study of strongly correlated systems, offering a scalable approach to explore and understand the complex physics governing these materials.

[30]  arXiv:2404.08804 (cross-list from cond-mat.soft) [pdf, ps, other]

Title: Hydroxide Transport and Mechanical Properties of Polyolefin-Based Anion Exchange Membranes from Atomistic Molecular Dynamics Simulations

Authors: Mohammed Al Otmi, Ping Lin, William Schertzer, Coray M. Colina, Rampi Ramprasad, Janani Sampath

Subjects: Soft Condensed Matter (cond-mat.soft); Materials Science (cond-mat.mtrl-sci)

Anion exchange membranes are used in alkaline fuel cells and offer a promising alternative to the more expensive proton exchange membrane fuel cells. However, hydroxide ion conductivity in anion exchange membranes is low, and the quest for membranes with superior ion conductivity, mechanical robustness, and chemical stability is ongoing. In this study, we use classical molecular dynamics simulations to study hydroxide ion transport and mechanical properties of eight different hydrated polyolefin-based membranes, to provide a molecular-level understanding of the structure-function relationships in these systems. We examine the microstructure of the membranes and find that polymers with narrow cavity size distribution have tighter packing of water molecules around hydroxide ions. We estimate the self-diffusion coefficient of water and hydroxide ions and find that water molecules have a higher diffusion than hydroxide ions across all systems. The trends in hydroxide diffusion align well with experimental conductivity measurements. Water facilitates hydroxide diffusion, and this is clearly observed when the hydration level is varied for the same polymer chemistry. In systems with narrow cavities and tightly bound hydroxide ions, hydroxide diffusion is the lowest, underscoring the fact that water channels facilitate hydroxide transport. Finally, we apply uniaxial deformation to calculate the mechanical properties of these systems and find that polymers with higher hydration levels show poor mechanical properties. Atomistic molecular dynamics models can accurately capture the trade-off between hydroxide transport and mechanical performance in anion exchange membranes and allow us to screen new candidates more efficiently.

[31]  arXiv:2404.08956 (cross-list from cond-mat.str-el) [pdf, ps, other]

Title: Emergent Griffiths-phase-like behavior in the ball-milled nanocrystalline Dy4RhAl and its implication

Authors: Kartik K Iyer, Kalobaran Maiti, S. Rayaprol, B A Chalke, E.V. Sampathkumaran

Comments: 11 pages, 5 figures

Journal-ref: J. Magn. Magn. Mater. 597 (2024) 172018

Subjects: Strongly Correlated Electrons (cond-mat.str-el); Materials Science (cond-mat.mtrl-sci)

We report the results of dc susceptibility and heat capacity measurements on the (ball-milled) nanocrystalline rare-earth (R) ternary compound, crystallizing in Gd4RhIn type, cubic Dy4RhAl compound. The bulk form of this compound has been known to undergo antiferromagnetic ordering at (TN=) 18 K with concomitant cluster spin glass anomalies. The present studies on the nano-form obtained by ball milling reveal that this antiferromagnetic ordering is suppressed with the reduction of particle size with no feature attributable to a well defined long-range magnetic ordering down to 1.8 K, but showing an inhomogeneous magnetism below 10 K. The point being stressed is that the results show the dominance of a feature around 30 K in the magnetic susceptibility data (well above TN of the bulk form) mimicking Griffiths phase. We infer that surface magnetism dominates before long range magnetic ordering occurs in this material.

[32]  arXiv:2404.09083 (cross-list from cond-mat.mes-hall) [pdf, ps, other]

Title: Interplay between electronic dephasing and localization in finite-sized Chern insulator

Authors: Yunhe Bai, Yuanzhao Li, Jianli Luan, Yang Chen, Zongwei Gao, Wenyu Song, Yitian Tong, Jinsong Zhang, Yayu Wang, Junjie Qi, Chui-Zhen Chen, Hua Jiang, X. C. Xie, Ke He, Yang Feng, Xiao Feng, Qi-Kun Xue

Comments: 20 pages, 4 figures

Subjects: Mesoscale and Nanoscale Physics (cond-mat.mes-hall); Materials Science (cond-mat.mtrl-sci)

Anderson localization is anticipated to play a pivotal role in the manifestation of the quantum anomalous Hall effect, akin to its role in conventional quantum Hall effects. The significance of Anderson localization is particularly pronounced in elucidating the reasons behind the fragility of the observed quantum anomalous Hall state in the intrinsic magnetic topological insulator MnBi2Te4 with a large predicted magnetic gap. Here, employing varying sized MnBi2Te4 micro/nano-structures fabricated from a single molecular-beam-epitaxy-grown thin film, we have carried out a systematic size- and temperature-dependent study on the transport properties of the films regarding the quantum anomalous Hall states. The low-temperature transport properties of the finite-sized MnBi2Te4 samples can be quantitatively understood through Anderson localization, which plays an indispensable role in stabilizing the ground states. At higher temperatures, the failure of electron localization induced by an excessively short electronic dephasing length is identified as the cause of deviation from quantization. The work reveals that electronic dephasing and localization are non-negligible factors in designing high-temperature quantum anomalous Hall systems.

[33]  arXiv:2404.09103 (cross-list from cond-mat.soft) [pdf, other]

Title: Ion Correlation Induced Non-monotonic Height Change and Microphase Separation of Polyelectrolyte Brushes

Authors: Chao Duan, Nikhil R. Agrawal, Rui Wang

Subjects: Soft Condensed Matter (cond-mat.soft); Materials Science (cond-mat.mtrl-sci); Statistical Mechanics (cond-mat.stat-mech); Chemical Physics (physics.chem-ph); Computational Physics (physics.comp-ph)

Modeling ion correlations in inhomogeneous polymers and soft matters with spatially varying ionic strength or dielectric permittivity remains a great challenge. Here, we develop a new theory which systematically incorporates electrostatic fluctuations into the self-consistent field theory for polymers. Applied to polyelectrolyte brushes, the theory predicts that ion correlations induce non-monotonic change of the brush height: collapse followed by reexpansion. The scaling analysis elucidates the competition between the repulsive osmotic pressure due to translational entropy and the attraction induced by ion correlations. We also clarify the absence of causal relationship between the brush collapse-reexpansion and the inversion of the surface electrostatic potential. Furthermore, strong ion correlations can trigger microphase separation, either in the lateral direction as pinned micelles or in the normal direction as oscillatory layers. Our theoretical predictions are in good agreement with the experimental results reported in the literature.

[34]  arXiv:2404.09132 (cross-list from quant-ph) [pdf, other]

Title: Quantum subspace expansion in the presence of hardware noise

Authors: João C. Getelina, Prachi Sharma, Thomas Iadecola, Peter P. Orth, Yong-Xin Yao

Comments: 12 pages, 6 figures

Subjects: Quantum Physics (quant-ph); Materials Science (cond-mat.mtrl-sci)

Finding ground state energies on current quantum processing units (QPUs) using algorithms like the variational quantum eigensolver (VQE) continues to pose challenges. Hardware noise severely affects both the expressivity and trainability of parametrized quantum circuits, limiting them to shallow depths in practice. Here, we demonstrate that both issues can be addressed by synergistically integrating VQE with a quantum subspace expansion, allowing for an optimal balance between quantum and classical computing capabilities and costs. We perform a systematic benchmark analysis of the iterative quantum-assisted eigensolver of [K. Bharti and T. Haug, Phys. Rev. A {\bf 104}, L050401 (2021)] in the presence of hardware noise. We determine ground state energies of 1D and 2D mixed-field Ising spin models on noisy simulators and on the IBM QPUs ibmq_quito (5 qubits) and ibmq_guadalupe (16 qubits). To maximize accuracy, we propose a suitable criterion to select the subspace basis vectors according to the trace of the noisy overlap matrix. Finally, we show how to systematically approach the exact solution by performing controlled quantum error mitigation based on probabilistic error reduction on the noisy backend fake_guadalupe.

[35]  arXiv:2404.09182 (cross-list from cond-mat.str-el) [pdf, other]

Title: Coexistence of interacting charge density waves in a layered semiconductor

Authors: B. Q. Lv, Alfred Zong, Dong Wu, Zhengwei Nie, Yifan Su, Dongsung Choi, Batyr Ilyas, Bryan T. Fichera, Jiarui Li, Edoardo Baldini, Masataka Mogi, Y.-B. Huang, Hoi Chun Po, Sheng Meng, Yao Wang, N. L. Wang, Nuh Gedik

Comments: To appear in PRL

Subjects: Strongly Correlated Electrons (cond-mat.str-el); Materials Science (cond-mat.mtrl-sci)

Coexisting orders are key features of strongly correlated materials and underlie many intriguing phenomena from unconventional superconductivity to topological orders. Here, we report the coexistence of two interacting charge-density-wave (CDW) orders in EuTe4, a layered crystal that has drawn considerable attention owing to its anomalous thermal hysteresis and a semiconducting CDW state despite the absence of perfect FS nesting. By accessing unoccupied conduction bands with time- and angle-resolved photoemission measurements, we find that mono- and bi-layers of Te in the unit cell host different CDWs that are associated with distinct energy gaps. The two gaps display dichotomous evolutions following photoexcitation, where the larger bilayer CDW gap exhibits less renormalization and faster recovery. Surprisingly, the CDW in the Te monolayer displays an additional momentum-dependent gap renormalization that cannot be captured by density-functional theory calculations. This phenomenon is attributed to interlayer interactions between the two CDW orders, which account for the semiconducting nature of the equilibrium state. Our findings not only offer microscopic insights into the correlated ground state of EuTe4 but also provide a general non-equilibrium approach to understand coexisting, layer-dependent orders in a complex system.

[36]  arXiv:2404.09330 (cross-list from cond-mat.soft) [pdf, ps, other]

Title: A universal strategy for decoupling stiffness and extensibility polymer networks

Authors: Baiqiang Huang, Shifeng Nian, Li-Heng Cai

Comments: 4 figures

Subjects: Soft Condensed Matter (cond-mat.soft); Materials Science (cond-mat.mtrl-sci); Chemical Physics (physics.chem-ph)

Since the invention of polymer networks in the 19th century (e.g., crosslinked natural rubber by Goodyear), it has been a dogma that stiffer networks are less stretchable, a trade-off inherent to the molecular nature of polymer network strands. Here, we report a universal strategy for decoupling the stiffness and extensibility of single-network elastomers. Instead of using linear polymers as network strands, we use foldable bottlebrush polymers, which feature a collapsed backbone grafted with many linear side chains. Upon elongation, the collapsed backbone unfolds to release stored length, enabling remarkable extensibility. By contrast, the network elastic modulus is inversely proportional to the network strand mass and is determined by the side chains. We validate this concept by creating a series of unentangled single-network elastomers with nearly constant Young's modulus (30 kPa) while increasing tensile breaking strain by 40-fold, from 20% to 800%. We show that this strategy applies to networks of different polymer species and topologies. Our discovery opens an avenue for developing polymer networks with extraordinary mechanical properties.

[37]  arXiv:2404.09355 (cross-list from cond-mat.soft) [pdf, other]

Title: Shape equilibria of vesicles with rigid planar inclusions

Authors: Geunwoong Jeon, Justin Fagnoni, Hao Wan, Maria M. Santore, Gregory M. Grason

Comments: 15 pages, 13 figures, 3 appendices

Subjects: Soft Condensed Matter (cond-mat.soft); Materials Science (cond-mat.mtrl-sci)

Motivated by recent studies of two-phase lipid vesicles possessing 2D solid domains integrated within a fluid bilayer phase, we study the shape equilibria of closed vesicles possessing a single planar, circular inclusion. While 2D solid elasticity tends to expel Gaussian curvature, topology requires closed vesicles to maintain an average, non-zero Gaussian curvature leading to an elementary mechanism of shape frustration that increases with inclusion size. We study elastic ground states of the Helfrich model of the planar-fluid composite vesicles, analytically and computationally, as a function of planar fraction and reduced volume. Notably, we show that incorporation of a planar inclusion of only a few percent dramatically shifts the ground state shapes of vesicles from predominantly {\it prolate} to {\it oblate}, and moreover, shifts the optimal surface to volume ratio far from spherical shapes. We show that for sufficiently small planar inclusions, the elastic ground states break symmetry via a complex variety of asymmetric oblate, prolate, and triaxial shapes, while inclusion sizes above about $8\%$ drive composite vesicles to adopt axisymmetric oblate shapes. These predictions cast useful light on the emergent shape and mechanical responses of fluid-solid composite vesicles.

[38]  arXiv:2404.09373 (cross-list from physics.chem-ph) [pdf, other]

Title: Use of multigrids to reduce the cost of performing interpolative separable density fitting

Authors: Kori E. Smyser, Alec White, Sandeep Sharma

Subjects: Chemical Physics (physics.chem-ph); Materials Science (cond-mat.mtrl-sci); Computational Physics (physics.comp-ph)

In this article, we present an interpolative separable density fitting (ISDF) based algorithm to calculate exact exchange in periodic mean field calculations. In the past, decomposing the two-electron integrals into tensor hypercontraction (THC) form using ISDF was the most expensive step of the entire mean field calculation. Here we show that by using a multigrid-ISDF algorithm both the memory and the CPU cost of this step can be reduced. The CPU cost is brought down from cubic scaling to quadratic scaling with a low computational prefactor which reduces the cost by almost two orders of magnitude. Thus, in the new algorithm, the cost of performing ISDF is largely negligible compared to other steps. Along with the CPU cost, the memory cost of storing the factorized two-electron integrals is also reduced by a factor of up to 35. With the current algorithm, we can perform Hartree-Fock calculations on a Diamond supercell containing more than 17,000 basis functions and more than 1,500 electrons on a single node with no disk usage. For this calculation, the cost of constructing the exchange matrix is only a factor of four slower than the cost of diagonalizing the Fock matrix. Augmenting our approach with linear scaling algorithms can further speed up the calculations.

[39]  arXiv:2404.09440 (cross-list from physics.app-ph) [pdf, ps, other]

Title: Electron Beam Restructuring of Quantum Emitters in Hexagonal Boron Nitride

Authors: Sergei Nedić, Karin Yamamura, Angus Gale, Igor Aharonovich, Milos Toth

Subjects: Applied Physics (physics.app-ph); Materials Science (cond-mat.mtrl-sci)

Hexagonal boron nitride (hBN) holds promise as a solid state, van der Waals host of single photon emitters for on-chip quantum photonics. The B-centre defect emitting at 436 nm is particularly compelling as it can be generated by electron beam irradiation. However, the emitter generation mechanism is unknown, the robustness of the method is variable, and it has only been applied successfully to thick flakes of hBN (>> 10 nm). Here, we use in-situ time-resolved cathodoluminescence (CL) spectroscopy to investigate the kinetics of B-centre generation. We show that the generation of B-centres is accompanied by quenching of a carbon-related emission at ~305 nm and that both processes are rate-limited by electromigration of defects in the hBN lattice. We identify problems that limit the efficacy and reproducibility of the emitter generation method, and solve them using a combination of optimized electron beam parameters and hBN pre- and post-processing treatments. We achieve B-centre quantum emitters in hBN flakes as thin as 8 nm, elucidate the mechanisms responsible for electron beam restructuring of quantum emitters in hBN, and gain insights towards identification of the atomic structure of the B-centre quantum emitter.

[40]  arXiv:2404.09527 (cross-list from cond-mat.str-el) [pdf, other]

Title: Dynamical Mean Field Theory for Real Materials on a Quantum Computer

Authors: Johannes Selisko, Maximilian Amsler, Christopher Wever, Yukio Kawashima, Georgy Samsonidze, Rukhsan Ul Haq, Francesco Tacchino, Ivano Tavernelli, Thomas Eckl

Comments: 25 pages, 6 figures, supplementary information

Subjects: Strongly Correlated Electrons (cond-mat.str-el); Materials Science (cond-mat.mtrl-sci); Superconductivity (cond-mat.supr-con); Quantum Physics (quant-ph)

Quantum computers (QC) could harbor the potential to significantly advance materials simulations, particularly at the atomistic scale involving strongly correlated fermionic systems where an accurate description of quantum many-body effects scales unfavorably with size. While a full-scale treatment of condensed matter systems with currently available noisy quantum computers remains elusive, quantum embedding schemes like dynamical mean-field theory (DMFT) allow the mapping of an effective, reduced subspace Hamiltonian to available devices to improve the accuracy of ab initio calculations such as density functional theory (DFT). Here, we report on the development of a hybrid quantum-classical DFT+DMFT simulation framework which relies on a quantum impurity solver based on the Lehmann representation of the impurity Green's function. Hardware experiments with up to 14 qubits on the IBM Quantum system are conducted, using advanced error mitigation methods and a novel calibration scheme for an improved zero-noise extrapolation to effectively reduce adverse effects from inherent noise on current quantum devices. We showcase the utility of our quantum DFT+DMFT workflow by assessing the correlation effects on the electronic structure of a real material, Ca2CuO2Cl2, and by carefully benchmarking our quantum results with respect to exact reference solutions and experimental spectroscopy measurements.

[41]  arXiv:2404.09669 (cross-list from physics.optics) [pdf, ps, other]

Title: Localized Resonant Phonon Polaritons in Biaxial Nanoparticles

Authors: Daniel Beitner, Asaf Farhi, Ravindra Kumar Nitharwal, Tejendra Dixit, Tzvia Beitner, Shachar Richter, SivaRama Krishnan, Haim Suchowski

Comments: 15 pages, 4 figures

Subjects: Optics (physics.optics); Materials Science (cond-mat.mtrl-sci)

The discovery of localized plasmon polariton resonances has been pivotal in enabling tunability of the optical resonance. Recently, extensive research efforts have aimed to expand these achievements to other polaritonic states that exhibit less loss and in other spectral regions. However, these efforts were limited to isotropic or uniaxial structures, and an eigenmode theory was derived only for isotropic particles. Here, we present a breakthrough in synthesizing biaxial nanostructures that exhibit localized hyperbolic phonon resonances with high Q-factors in the mid-infrared. Furthermore, we develop a theory that predicts high-order resonances in anisotropic particles with coupling between the axial permittivites. Finally, we confirm the theoretical predictions through near-field measurements, which demonstrate the existence of both the first and higher-order resonant modes. Our findings provide the foundation for designing a new generation of anisotropic resonators with various applications in the mid-IR range. Our analysis applies to other fields, such as quasi-magnetostatics and heat conduction.

[42]  arXiv:2404.09806 (cross-list from physics.app-ph) [pdf, other]

Title: Martensite decomposition kinetics in additively manufactured Ti-6Al-4V alloy: in-situ characterisation and phase-field modelling

Authors: A.D. Boccardo, Z. Zou, M. Simonelli, M. Tong, J. Segurado, S.B. Leen, D. Tourret

Subjects: Applied Physics (physics.app-ph); Materials Science (cond-mat.mtrl-sci)

Additive manufacturing of Ti-6Al-4V alloy via laser powder-bed fusion leads to non-equilibrium $\alpha'$ martensitic microstructures, with high strength but poor ductility and toughness. These properties may be modified by heat treatments, whereby the $\alpha'$ phase decomposes into equilibrium $\alpha+\beta$ structures, while possibly conserving microstructural features and length scales of the $\alpha'$ lath structure. Here, we combine experimental and computational methods to explore the kinetics of martensite decomposition. Experiments rely on in-situ characterisation (electron microscopy and diffraction) during multi-step heat treatment from 400$^{\circ}$C up to the alloy $\beta$-transus temperature (995$^{\circ}$C). Computational simulations rely on an experimentally-informed computationally-efficient phase-field model. Experiments confirmed that as-built microstructures were fully composed of martensitic $\alpha'$ laths. During martensite decomposition, nucleation of the $\beta$ phase occurs primarily along $\alpha'$ lath boundaries, with traces of $\beta$ nucleation along crystalline defects. Phase-field results, using electron backscatter diffraction maps of as-built microstructures as initial conditions, are compared directly with in-situ characterisation data. Experiments and simulations confirmed that, while full decomposition into stable $\alpha+\beta$ phases may be complete at 650$^{\circ}$C provided sufficient annealing time, visible morphological evolution of the microstructure was only observed for $T\geq\,$700$^{\circ}$C, without modification of the prior-$\beta$ grain structure.

[43]  arXiv:2404.09813 (cross-list from cond-mat.other) [pdf, ps, other]

Title: Four center integrals for Coulomb interactions in small molecules

Authors: Garry Goldstein

Comments: Comments welcome

Subjects: Other Condensed Matter (cond-mat.other); Materials Science (cond-mat.mtrl-sci); Chemical Physics (physics.chem-ph)

In this work we make some progress on studying four center integrals for the Coulomb energy for both Hartree Fock (HF) and Density Functional Theory (DFT) calculations for small molecules. We consider basis wave functions of the form of an arbitrary radial wave function multiplied by a spherical harmonic and study four center Coulomb integrals for them. We reformulated these Coulomb four center integrals in terms of some derivatives of integrals of nearly factorable functions which then depend on the Bessel transform of the radial wave functions considered.

[44]  arXiv:2404.09896 (cross-list from cs.LG) [pdf, ps, other]

Title: Accelerating Ensemble Error Bar Prediction with Single Models Fits

Authors: Vidit Agrawal, Shixin Zhang, Lane E. Schultz, Dane Morgan

Comments: 14 pages, 4 figures, 1 table

Subjects: Machine Learning (cs.LG); Materials Science (cond-mat.mtrl-sci)

Ensemble models can be used to estimate prediction uncertainties in machine learning models. However, an ensemble of N models is approximately N times more computationally demanding compared to a single model when it is used for inference. In this work, we explore fitting a single model to predicted ensemble error bar data, which allows us to estimate uncertainties without the need for a full ensemble. Our approach is based on three models: Model A for predictive accuracy, Model $A_{E}$ for traditional ensemble-based error bar prediction, and Model B, fit to data from Model $A_{E}$, to be used for predicting the values of $A_{E}$ but with only one model evaluation. Model B leverages synthetic data augmentation to estimate error bars efficiently. This approach offers a highly flexible method of uncertainty quantification that can approximate that of ensemble methods but only requires a single extra model evaluation over Model A during inference. We assess this approach on a set of problems in materials science.

[45]  arXiv:2404.09904 (cross-list from cond-mat.mes-hall) [pdf, other]

Title: Electrical control of valley polarized charged biexcitons in monolayer WS$_2$

Authors: Sarthak Das, Ding Huang, Ivan Verzhbitskiy, Zi-En Ooi, Chit Siong Lau, Rainer Lee, Calvin Pei Yu Wong, Kuan Eng Johnson Goh

Subjects: Mesoscale and Nanoscale Physics (cond-mat.mes-hall); Materials Science (cond-mat.mtrl-sci)

Excitons are key to the optoelectronic applications of van der Waals semiconductors with the potential for versatile on-demand tuning of properties. Yet, their electrical manipulation is complicated by their inherent charge neutrality and the additional loss channels induced by electrical doping. We demonstrate the dynamic control of valley polarization in charged biexciton (quinton) states of monolayer tungsten disulfide, achieving up to a sixfold increase in the degree of circular polarization under off-resonant excitation. In contrast to the weak direct tuning of excitons typically observed using electrical gating, the quinton photoluminescence remains stable, even with increased scattering from electron doping. By exciting at the exciton resonances, we observed the reproducible non-monotonic switching of the charged state population as the electron doping is varied under gate bias, indicating a coherent interplay between neutral and charged exciton states.

Replacements for Tue, 16 Apr 24

[46]  arXiv:2308.13692 (replaced) [pdf, other]

Title: Enhanced Spin Hall Ratio in Two-Dimensional Semiconductors

Authors: Jiaqi Zhou, Samuel Poncé, Jean-Christophe Charlier

Comments: 6 pages, 5 figures

Subjects: Materials Science (cond-mat.mtrl-sci); Computational Physics (physics.comp-ph)

[47]  arXiv:2310.03857 (replaced) [pdf, ps, other]

Title: Resolving Length Scale Dependent Transient Disorder Through an Ultrafast Phase Transition

Authors: Jack Griffiths, Ana Flávia Suzana, Longlong Wu, Samuel D. Marks, Vincent Esposito, Sébastien Boutet, Paul G. Evans, J. F. Mitchell, Mark P. M. Dean, David A. Keen, Ian Robinson, Simon J. L. Billinge, Emil S. Bozin

Comments: 14 page manuscript with 4 figures. 13 page Supplementary with 17 figures. 27 pages and 21 figures in total

Subjects: Materials Science (cond-mat.mtrl-sci)

[48]  arXiv:2311.13130 (replaced) [pdf, other]

Title: Inducing a Tunable Skyrmion-Antiskyrmion System through Ion Beam Modification of FeGe Films

Authors: M. B. Venuti, Xiyue S. Zhang, Eric J Lang, Sadhvikas J. Addamane, Hanjong Paik, Portia Allen, Peter Sharma, David Muller, Khalid Hattar, Tzu-Ming Lu, Serena Eley

Subjects: Materials Science (cond-mat.mtrl-sci); Mesoscale and Nanoscale Physics (cond-mat.mes-hall); Strongly Correlated Electrons (cond-mat.str-el)

[49]  arXiv:2401.11336 (replaced) [pdf, ps, other]

Title: Stochastic density functional theory combined with Langevin dynamics for warm dense matter

Authors: Rebecca Efrat Hadad, Argha Roy, Eran Rabani, Ronald Redmer, Roi Baer

Subjects: Materials Science (cond-mat.mtrl-sci); Computational Physics (physics.comp-ph); Plasma Physics (physics.plasm-ph)

[50]  arXiv:2402.17064 (replaced) [pdf, ps, other]

Title: The influence of the phase and structural state on the low-temperature elastic properties of molybdenum-alloyed non-equiatomic high-entropy alloys of the Fe-Co-Ni-Cr system

Authors: Yurii Semerenko, Elena Tabachnikova, Tetiana Hryhorova, Sergii Shumilin, Viktor Zoryansky (B. Verkin Institute for Low Temperature Physics and Engineering of the NAS of Ukraine, Kharkiv, Ukraine)

Comments: 4 pages, 1 figure

Subjects: Materials Science (cond-mat.mtrl-sci); Other Condensed Matter (cond-mat.other)

[51]  arXiv:2402.18957 (replaced) [pdf, other]

Title: Vibrational properties differ between halide and chalcogenide perovskite semiconductors, and it matters for optoelectronic performance

Authors: K. Ye (1), M. Menahem (2), T. Salzillo (3), F. Knoop (4), B. Zhao (5), S. Niu (5), O. Hellman (4 and 6), J. Ravichandran (6 and 7 and 8), R. Jaramillo (1), O. Yaffe (2)

Comments: Main text - 12 pages with 5 figures and 1 table. Supplemental text - 16 pages with 6 figures and 5 tables

Subjects: Materials Science (cond-mat.mtrl-sci)

[52]  arXiv:2404.01214 (replaced) [pdf, other]

Title: High-temperature domain wall current in Mg-doped lithium niobate single crystals up to 400°C

Authors: Uliana Yakhnevych, Marlo Kunzner, Leonard M. Verhoff, Julius Ratzenberger, Elke Beyreuther, Michael Rüsing, Simone Sanna, Lukas M. Eng, Holger Fritze

Comments: 5 pages, 4 figures; with included supplementary material (6 pages, 9 figures)

Subjects: Materials Science (cond-mat.mtrl-sci)

[53]  arXiv:2404.04980 (replaced) [pdf, ps, other]

Title: Element-specific ultrafast lattice dynamics in FePt nanoparticles

Authors: Diego Turenne, Igor Vaskivskiy, Klaus Sokolowski-Tinten, Xijie Wang, Alexander H. Reid, Xiaoshe Shen, Ming-Fu Lin, Suji Park, Stephen Weathersby, Michael Kozina, Matthias Hoffmann, Jian Wang, Jakub Sebesta, Yukiko K. Takahashi, Oscar Grånäs, Peter Oppeneer, Hermann A. Dürr

Comments: 21 pages, 5 figures

Subjects: Materials Science (cond-mat.mtrl-sci)

[54]  arXiv:2303.06030 (replaced) [pdf, ps, other]

Title: Semiclassical transport in two-dimensional Dirac materials with spatially variable tilt

Authors: Abolfath Hosseinzadeh, Seyed Akbar Jafari

Subjects: Mesoscale and Nanoscale Physics (cond-mat.mes-hall); Materials Science (cond-mat.mtrl-sci); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Theory (hep-th)

[55]  arXiv:2309.11428 (replaced) [pdf, ps, other]

Title: Off-shell selfenergy for 1-D Fermi liquids

Authors: Klaus Morawetz, Vinod Ashokan, Kare Narain Pathak, Neil Drummond

Subjects: Strongly Correlated Electrons (cond-mat.str-el); Materials Science (cond-mat.mtrl-sci)

[56]  arXiv:2311.03107 (replaced) [pdf, other]

Title: Longitudinal Polaritons in Crystals

Authors: Eduardo B. Barros, Stephanie Reich

Subjects: Optics (physics.optics); Materials Science (cond-mat.mtrl-sci)

[57]  arXiv:2312.10832 (replaced) [pdf, ps, other]

Title: Moving frame theory of zero-bias photocurrent on the surface of topological insulators

Authors: S. A. Jafari

Comments: 5 pages, no fig

Subjects: Mesoscale and Nanoscale Physics (cond-mat.mes-hall); Materials Science (cond-mat.mtrl-sci); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Theory (hep-th)

[58]  arXiv:2402.09251 (replaced) [pdf, ps, other]

Title: Universal Machine Learning Kohn-Sham Hamiltonian for Materials

Authors: Yang Zhong, Hongyu Yu, Jihui Yang, Xingyu Guo, Hongjun Xiang, Xingao Gong

Comments: 20 pages, 9 figures

Subjects: Computational Physics (physics.comp-ph); Materials Science (cond-mat.mtrl-sci); Artificial Intelligence (cs.AI)

[59]  arXiv:2403.07846 (replaced) [pdf, other]

Title: Topology-induced symmetry breaking: a demonstration in antiferromagnetic magnons on a Möbius strip

Authors: Kuangyin Deng, Ran Cheng

Subjects: Mesoscale and Nanoscale Physics (cond-mat.mes-hall); Materials Science (cond-mat.mtrl-sci); Quantum Physics (quant-ph)

• New submissions
• Cross-lists
• Replacements