论文标题
Mn $ a_ {2} $$ x_ {4} $（a = bi，sb; x = se，te）的拓扑阶段
Topological Phases of Mn$A_{2}$$X_{4}$ (A=Bi, Sb; X = Se, Te) under Magnetic Field
论文作者
论文摘要
电子拓扑的概念和相关的拓扑保护为开发下一代设备带来了绝佳的机会。理想情况下，磁性拓扑材料（MTM）应在费米能量（EF）处具有其Dirac/Weyl点和/或相关的质量间隙，或者容易调节，以便可以通过外部扰动将其放置在EF上，例如电场门控，化学替代或掺杂。三维抗铁磁（AFM）材料（如Mn $ bi_ {2} $$ x_ {4} $（x = se，te，te），它们具有强大的旋转轨道耦合（SOC）和损坏的时间反向对称性（TRS），这是由于磁性的效果而引起的。在存在外部磁场的情况下，第一个固有的磁性绝缘子家族Mn $ bi_ {2} $$ TE_ {4} $（MBT）。我们的计算表明，大量菱形（r $ \ overline {3} $ m）mn $ a_ {2} $$ x_ {4} $（a = sb，bi; x = se，te）的拓扑阶段取决于旋转方向和化学。 Mn $ sb_ {2} $$ SE_ {4} $（MSS）的抗磁磁（AFM）基态是一个琐碎的绝缘子，而Mn $ bi_ {2} $$ se_ se_ {4} $（MBS）的AFM基态是轴突绝缘子。在存在足够强大的外部磁场的情况下，两种材料都成为淋巴结点或淋巴结线Weyl半法。 Mn $ SB_ {2} $$ TE_ {4} $（MST）的AFM基态是轴绝缘子。 MST是一种II型Weyl半学，旋转在$ \ hat {z} $ - 方向上对齐，但在平面内旋转的倒置频带间隙变得绝缘。同样，MBT的AFM相是轴突绝缘子，但在铁磁相中仍具有倒置间隙的绝缘。此外，我们通过用SB原子代替BI原子，证明了Mn $ BI_ {2} $$ TE_ {4} $（MBT）的拓扑阶段的演变。
The concept of electronic topology and the associated topological protection brings excellent opportunities for developing next-generation devices. Ideally, magnetic topological materials (MTM) should have their Dirac/Weyl points and/or associated mass gaps at the Fermi energy (EF) or be readily tunable such that they can be placed at EF via external perturbations such as electric field gating, chemical substitutions, or doping. Three-dimensional antiferromagnetic (AFM) materials like Mn$Bi_{2}$$X_{4}$ (X=Se, Te) that have strong spin-orbit coupling (SOC) and broken time-reversal symmetry (TRS) due to magnetic ordering have been the subject of enormous interest.. In this work, using density functional theory (DFT), we have studied the electronic properties and topological phases of the first intrinsic magnetic topological insulator family Mn$Bi_{2}$$Te_{4}$ (MBT) in the presence of an external magnetic field. Our calculations reveal that the topological phase of bulk rhombohedral (R$\overline{3}$m) Mn$A_{2}$$X_{4}$ (A = Sb, Bi; X=Se, Te) depends on the spin direction and the chemistry. The antiferromagnetic (AFM) ground state of Mn$Sb_{2}$$Se_{4}$ (MSS) is a trivial insulator, whereas the AFM ground state of Mn$Bi_{2}$$Se_{4}$(MBS) is an Axion insulator. Both materials become nodal point or nodal line Weyl semimetals in the presence of a sufficiently strong external magnetic field. The AFM ground state of Mn$Sb_{2}$$Te_{4}$ (MST) is an Axion insulator. MST is a type-II Weyl semimetal with spins aligned in the $\hat{Z}$-direction, but becomes insulating with an inverted band gap for spins in-plane. Similarly, the AFM phase of MBT is an Axion insulator, but remains insulating with an inverted gap in the ferromagnetic phase. Additionally, we demonstrated the evolution of the topological phase of Mn$Bi_{2}$$Te_{4}$ (MBT) by substituting the Bi atoms with the Sb atoms.
