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Condensed Matter > Strongly Correlated Electrons
Title: Peierls transition, ferroelectricity, and spin-singlet formation in the monolayer VOI$_2$
(Submitted on 24 Dec 2020 (v1), last revised 23 Feb 2021 (this version, v2))
Abstract: Using {\it ab initio} density functional theory and single-orbital Hubbard model calculations via the density matrix renormalization group method, we systematically studied the monolayer VOI$_2$ with a $3d^1$ electronic configuration. Our phonon calculations indicate that the orthorhombic $Pmm2$ FE-II phase is the most likely ground state, involving a ferroelectric distortion along the $a$-axis and V-V dimerization along the $b$-axis. Specifically, the "pseudo Jahn-Teller" effect caused by the coupling between empty V ($d_{xz/yz}$ and $d_{3z^2-r^2}$) and O $2p$ states is proposed as the mechanism that stabilizes the ferroelectric distortion from the paraelectric phase. Moreover, the half-filled metallic $d_{xy}$ band displays a Peierls instability along the $b$-axis, inducing a V-V dimerization. We also found very short-range antiferromagnetic coupling along the V-V chain due to the formation of nearly-decoupled spin singlets in the ground state.
Submission history
From: Yang Zhang Dr. [view email][v1] Thu, 24 Dec 2020 00:39:16 GMT (2142kb,D)
[v2] Tue, 23 Feb 2021 02:04:34 GMT (2158kb,D)
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