Geometric Hall effects in topological insulator heterostructures
Geometric Hall effects in topological insulator heterostructures
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DOI：
10.1038/nphys3671
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发表时间：
2016-06-01
期刊：
影响因子：
19.6
通讯作者：
Tokura, Y.
中科院分区：
文献类型：
--
作者：
Yasuda, K.;Wakatsuki, R.;Tokura, Y.
动量几何和实空间几何在凝聚态物质系统的电子动力学中发挥着重要作用。其中，与非平凡几何相关的贝里相可以成为电子横向运动的起源，产生各种几何效应，例如反常（1）、自旋（2）和拓扑霍尔效应（3-6）。在这里，我们报告了霍尔物理的两个非常规表现：异常霍尔效应的符号反转，以及磁性/非磁性拓扑绝缘体异质结构 Cr-x(Bi1-ySby)(2-x)Te-3/(Bi1-ySby)(2)Te-3 中拓扑霍尔效应的出现。反常霍尔效应中的符号反转是由体能带处的拉什巴分裂驱动的，这是由破坏的空间反转对称性引起的。相反，拓扑霍尔效应出现在低于居里温度的宽温度范围内，在该区域中霍尔电阻的磁场依赖性很大程度上偏离磁化强度。其起源被认为是由 Dzyaloshinskii-Moriya 相互作用诱导的尼尔型斯格明子的形成。
Geometry, both in momentum and in real space, plays an important role in the electronic dynamics of condensed matter systems. Among them, the Berry phase associated with nontrivial geometry can be an origin of the transverse motion of electrons, giving rise to various geometric effects such as the anomalous(1), spin(2) and topological Hall effects(3-6). Here, we report two unconventional manifestations of Hall physics: a sign-reversal of the anomalous Hall effect, and the emergence of a topological Hall effect in magnetic/non-magnetic topological insulator heterostructures, Cr-x(Bi1-ySby)(2-x)Te-3/(Bi1-ySby)(2)Te-3. The sign-reversal in the anomalous Hall effect is driven by a Rashba splitting at the bulk bands, which is caused by the broken spatial inversion symmetry. Instead, the topological Hall effect arises in a wide temperature range below the Curie temperature, in a region where the magnetic-field dependence of the Hall resistance largely deviates from the magnetization. Its origin is assigned to the formation of a Neel-type skyrmion induced by the Dzyaloshinskii-Moriya interaction.