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Condensed Matter > Strongly Correlated Electrons
Title: Single pair of Weyl nodes in the spin-canted structure of EuCd$_2$As$_2$
(Submitted on 2 Dec 2020 (v1), last revised 29 Jun 2022 (this version, v3))
Abstract: Time reversal symmetry breaking Weyl semimetals are unique among Weyl materials in allowing the minimal number of Weyl points thus offering the clearest signatures of the associated physics. Here we present neutron diffraction, density functional theory and transport measurement results which indicate that EuCd$_2$As$_2$ , under ambient field, strain and pressure, is such a material with a single pair of Weyl points. Our work reveals a magnetic structure (magnetic space group $C2'/m'$) with Eu moments pointing along the [210] direction in-plane and canted $\sim$ 30$^{\circ}$ out-of-plane. Density functional theory calculations using this structure show that the observed canting drastically alters the relevant electronic bands, relative to the in-plane order, leading to a single set of well defined Weyl points. Furthermore, we find the canting angle can tune the distance of the Weyl points above the Fermi level, with the smallest distance at low canting angles. Finally, transport measurements of the anomalous Hall Effect and longitudinal magnetoresistance exhibit properties indicative of a chiral anomaly, thus supporting the neutron scattering and DFT results suggesting EuCd$_2$As$_2$ is close to the ideal situation of the Weyl "Hydrogen atom".
Submission history
From: Keith Taddei Dr [view email][v1] Wed, 2 Dec 2020 21:57:39 GMT (5369kb,D)
[v2] Fri, 4 Dec 2020 02:41:16 GMT (5369kb,D)
[v3] Wed, 29 Jun 2022 12:11:32 GMT (4259kb,D)
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