论文标题
向Weyl State的拓扑过渡到散装bi $ _2 $ SE $ _3 $：静水压力和掺杂的效果
Topological transitions to Weyl states in bulk Bi$_2$Se$_3$: Effect of hydrostatic pressure and doping
论文作者
论文摘要
BI $ _2 $ SE $ _3 $，一种分层的三维（3D）材料，由于表面状态的存在而表现出拓扑绝缘性能，并且在散装中具有0.3 eV的带状。我们从第一原则的角度研究了液压压力$ p $ $ p $ $ p $和与稀土元素的兴奋剂在该材料的拓扑方面。我们的研究表明，在中等压力> $ 7.9 $ 7.9 GPA的情况下，批量电子性质显示出由于带反转而导致的隔热到Weyl半金属状态的过渡。该电子拓扑转换可能与从分层的范德华材料到观察到的3D系统的结构变化相关，在$ p $ = 7.9 GPa时。在$ $ $ $的情况下，州的密度在Fermi-Energy上具有显着价值。与BI $ _2 $ SE $ _3 $层之间的小掺杂分数相结合的GD将系统驱动到金属的抗铁磁性状态，而Weyl节点低于Fermi-Energy。在Weyl节点，由于GD原子上的大磁矩引起的有限局部场，逆转对称性被打破。但是，用GD代替BI会诱导抗铁磁阶，并增加直接带隙。我们的研究提供了新颖的方法来调整拓扑转变，尤其是在3D拓扑材料中捕获难以捉摸的Weyl半准状态时。
Bi$_2$Se$_3$, a layered three dimensional (3D) material, exhibits topological insulating properties due to presence of surface states and a band gap of 0.3 eV in the bulk. We study the effect hydrostatic pressure $P$ and doping with rare earth elements on the topological aspect of this material in bulk from a first principles perspective. Our study shows that under a moderate pressure of P$>$7.9 GPa, the bulk electronic properties show a transition from an insulating to a Weyl semi-metal state due to band inversion. This electronic topological transition may be correlated to a structural change from a layered van der Waals material to a 3D system observed at $P$=7.9 GPa. At large $P$ density of states have significant value at the Fermi-energy. Intercalating Gd with a small doping fraction between Bi$_2$Se$_3$ layers drives the system to a metallic anti-ferromagnetic state, with Weyl nodes below the Fermi-energy. At the Weyl nodes time reversal symmetry is broken due to finite local field induced by large magnetic moments on Gd atoms. However, substituting Bi with Gd induces anti-ferromagnetic order with an increased direct band gap. Our study provides novel approaches to tune topological transitions, particularly in capturing the elusive Weyl semimetal states, in 3D topological materials.
