Department of Electrical Engineering, University of California , Los Angeles, California 90095, United States.
ACS Nano. 2013 Oct 22;7(10):9205-12. doi: 10.1021/nn4038145. Epub 2013 Sep 30.
Breaking the time-reversal-symmetry of topological insulators through magnetic doping has led to exotic physical discoveries. Here, we report the gate-dependent magneto-transport measurements on the Cr-doped (BixSb1-x)2Te3 thin films. With effective top-gate modulations, we demonstrate the presence of both the hole-mediated RKKY coupling and carrier-independent van Vleck magnetism in the magnetic TI systems. Most importantly, by varying the Cr doping concentrations from 2% to 20%, we unveil the interplay between the two magnetic orders and establish the valid approach to either enhance or suppress each individual contribution. The electric-field-controlled ferromagnetisms identified in the Cr-doped TI materials will serve as the fundamental step to further explore the TRS-breaking TI systems, and it may also help to expand the functionality of TI-based device for spintronics applications.
通过磁性掺杂打破拓扑绝缘体的时间反演对称性已经导致了奇异的物理发现。在这里，我们报告了对 Cr 掺杂（BixSb1-x）2Te3 薄膜的门控磁输运测量。通过有效的顶栅调制，我们证明了在磁性 TI 系统中存在空穴介导的 RKKY 耦合和与载流子无关的范弗莱克磁性。最重要的是，通过将 Cr 掺杂浓度从 2%变化到 20%，我们揭示了两种磁有序之间的相互作用，并建立了增强或抑制每个贡献的有效方法。在 Cr 掺杂 TI 材料中识别出的电场控制铁磁性将作为进一步探索 TRS 破坏 TI 系统的基本步骤，并且它也可能有助于扩展基于 TI 的器件在自旋电子学应用中的功能。
