Field-tunable Weyl points and large anomalous Hall effects in degenerate magnetic semiconductor EuMg${}_2$Bi${}_2$

Abstract

Magnets, with topologically-nontrivial Dirac/Weyl points, have recently attracted significant attention owing to the unconventional physical properties, such as large anomalous Hall effects. However, they typically have a high carrier density and complicated band structure near the Fermi energy. In this study, we report degenerate magnetic semiconductor EuMg${}_2$Bi${}_2$, which exhibits a single valley at the $\Gamma$ point, where the field-tunable Weyl points form via the magnetic exchange interaction with the local Eu spins. By the high-field measurements on high-quality single crystals, we observed the quantum oscillations in resistivity, elastic constant, and surface impedance, which enabled us to determine the position of the Fermi energy. In combination with the first-principles calculation, we revealed that the Weyl points are located in the vicinity of the Fermi energy when the Eu spins are fully polarized. Furthermore, we observed large anomalous Hall effect (Hall angle ${\Theta }_{\mathrm{AH}}\sim 0.07$) in the forced ferromagnetic phase, which is consistent with this field variation of band structure.

18 pages, 4 figures

References in corpus (12)

• Intrinsic vs. extrinsic anomalous Hall effect in ferromagnets
• Quantum Hall effect in a bulk antiferromagnet EuMnBi${}_2$ with magnetically confined two-dimensional Dirac fermions
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• Topological Kagome magnet Co3Sn2S2 thin flakes with high electron mobility and large anomalous Hall effect
• Magnetic, thermal, and electronic-transport properties of EuMg2Bi2 single crystals
• A-type antiferromagnetic order in semiconducting EuMg${}_2$Sb${}_2$ single crystals
• Zero-field magnetic ground state of EuMg${}_2$Bi${}_2$
• Maximizing intrinsic anomalous Hall effect by controlling the Fermi level in simple Weyl semimetal films
• Magnetic generation and switching of topological quantum phases in a trivial semimetal $\alpha {-\mathrm{EuP}}_3$

Cited by in corpus (3)

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• Nonmonotonic Hall effect of Weyl semimetals under magnetic field
• Topological Hall effect enhanced at magnetic transition fields in a frustrated magnet EuCd${}_2$