论文标题
脱位磁性半导体Eumg $ _2 $ bi $ _2 $
Field-tunable Weyl points and large anomalous Hall effects in degenerate magnetic semiconductor EuMg$_2$Bi$_2$
论文作者
论文摘要
磁铁具有拓扑不足的狄拉克/Weyl点，由于非常规的物理特性，例如较大的异常霍尔效应，最近引起了极大的关注。但是，它们通常在费米能量附近具有高载体密度和复杂的带结构。在这项研究中，我们报告了退化的磁性半导体EUMG $ _2 $ bi $ _2 $，该$ _2 $在$γ$点上展示了一个山谷，其中通过与本地欧盟旋转的磁交换相互作用，在其中形成了田间可调的Weyl点。通过对高质量单晶的高视野测量值，我们观察到电阻率，弹性常数和表面阻抗的量子振荡，这使我们能够确定费米能的位置。结合第一原理的计算，我们揭示了当欧盟自旋完全极化时，韦尔点位于费米能的附近。此外，我们在强制的铁磁阶段观察到了大的异常霍尔效应（霍尔角$θ_ {\ mathrm {ah}} \ sim0.07 $），这与带结构的磁场变化一致。
Magnets, with topologically-nontrivial Dirac/Weyl points, have recently attracted significant attention owing to the unconventional physical properties, such as large anomalous Hall effects. However, they typically have a high carrier density and complicated band structure near the Fermi energy. In this study, we report degenerate magnetic semiconductor EuMg$_2$Bi$_2$, which exhibits a single valley at the $Γ$ 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 $Θ_{\mathrm{AH}}\sim0.07$) in the forced ferromagnetic phase, which is consistent with this field variation of band structure.
