论文标题
强磁场下的二阶拓扑绝缘子：兰道水平，Zeeman效应和磁转运
Second-order topological insulator under strong magnetic field: Landau levels, Zeeman effect, and magnetotransport
论文作者
论文摘要
我们研究了受磁场的三维手性二阶拓扑绝缘子（SOTI）。通过其量规场，应用的磁场会影响晶格上的电子运动，并通过Zeeman效应影响电子自旋。我们将两种方法比较了问题：有效的表面理论和完整的晶格计算。表面理论预测在每个间隙的表面上都有巨大的狄拉克频谱，一旦表面被磁通量刺穿，就会产生Landau水平。表面理论定性地与我们的晶格计算一致，可以准确预测表面狄拉克带边缘处状态的旋转和轨道成分。在晶格理论的背景下，我们计算有和没有磁场的光谱，并在应用量规场时与表面理论偏离。发现最低的Landau水平的能量比表面理论所预测的更接近零，该表面理论导致可观察到的磁转运符号：在表面间隙内部，存在一个或两个手性铰链模式在任何方向上均匀的一个或两个指导模式，将差分电导率量化至一个或两个电导率量子。
We study a three-dimensional chiral second order topological insulator (SOTI) subject to a magnetic field. Via its gauge field, the applied magnetic field influences the electronic motion on the lattice, and via the Zeeman effect, the field influences the electronic spin. We compare two approaches to the problem: an effective surface theory, and a full lattice calculation. The surface theory predicts a massive Dirac spectrum on each of the gapped surfaces, giving rise to Landau levels once the surfaces are pierced by magnetic flux. The surface theory qualitatively agrees with our lattice calculations, accurately predicting the surface gap as well as the spin and orbital components of the states at the edges of the surface Dirac bands. In the context of the lattice theory, we calculate the spectrum with and without magnetic field and find a deviation from the surface theory when a gauge field is applied. The energy of the lowest-lying Landau level is found closer to zero than is predicted by the surface theory, which leads to an observable magnetotransport signature: inside the surface gap, there exist different energy regions where either one or two chiral hinge modes propagate in either direction, quantizing the differential conductance to either one or two conductance quanta.
