Gate-tunable Intrinsic Anomalous Hall Effect in Epitaxial MnBi2Te4 Films,Nano Letters

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Gate-tunable Intrinsic Anomalous Hall Effect in Epitaxial MnBi2Te4 Films
Nano Letters ( IF 9.6 ) Pub Date : 2023-12-18 , DOI: 10.1021/acs.nanolett.3c02926
Shanshan Liu _{1,

2} , Jie-Xiang Yu ₃ , Enze Zhang ₁ , Zihan Li _{1,

2} , Qiang Sun _{4,

5} , Yong Zhang ₆ , Liwei Cao ₇ , Lun Li ₆ , Minhao Zhao _{1,

2} , Pengliang Leng _{1,

2} , Xiangyu Cao _{1,

2} , Ang Li ₇ , Jin Zou _{4,

5} , Xufeng Kou ₆ , Jiadong Zang ₈ , Faxian Xiu _{1,

2,

9,

10,

11}

Affiliation

State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China.
Shanghai Qi Zhi Institute, 41st Floor, AI Tower, No. 701 Yunjin Road, Xuhui District, Shanghai 200232, China.
School of Physical Science and Technology, Soochow University, Suzhou 215006, China.
Materials Engineering, The University of Queensland, Brisbane QLD 4072, Australia.
Centre for Microscopy and Microanalysis, The University of Queensland, Brisbane QLD 4072, Australia.
School of Information Science and Technology, ShanghaiTech University, Shanghai 201210, China.
Beijing Key Lab of Microstructure and Property of Advanced Material, Institute of Microstructure and Properties of Advanced Materials, Beijing University of Technology, Beijing 100124, China.
Department of Physics and Astronomy, University of New Hampshire, Durham, New Hampshire 03824, United States.
Institute for Nanoelectronic Devices and Quantum Computing, Fudan University, Shanghai 200433, China.
Zhangjiang Fudan International Innovation Center, Fudan University, Shanghai 201210, China.
Shanghai Research Center for Quantum Sciences, Shanghai 201315, China.

The anomalous Hall effect (AHE) is an important transport signature revealing topological properties of magnetic materials and their spin textures. Recently, MnBi₂Te₄ has been demonstrated to be an intrinsic magnetic topological insulator. However, the origin of its intriguing AHE behaviors remains elusive. Here, we demonstrate the Berry curvature-dominated intrinsic AHE in wafer-scale MnBi₂Te₄ films. By applying back-gate voltages, we observe an ambipolar conduction and n–p transition in ∼7-layer MnBi₂Te₄, where a quadratic relation between the AHE resistance and longitudinal resistance suggests its intrinsic AHE nature. In particular, for ∼3-layer MnBi₂Te₄, the AHE sign can be tuned from pristine negative to positive. First-principles calculations unveil that such an AHE reversal originated from the competing Berry curvature between oppositely polarized spin-minority-dominated surface states and spin-majority-dominated inner bands. Our results shed light on the underlying physical mechanism of the intrinsic AHE and provide new perspectives for the unconventional sign-tunable AHE.

中文翻译：

外延 MnBi2Te4 薄膜中的栅极可调本征反常霍尔效应

反常霍尔效应（AHE）是揭示磁性材料的拓扑特性及其自旋纹理的重要输运特征。最近，MnBi ₂ Te ₄已被证明是一种本征磁拓扑绝缘体。然而，其有趣的 AHE 行为的起源仍然难以捉摸。在这里，我们展示了晶圆级 MnBi ₂ Te ₄薄膜中贝里曲率主导的本征 AHE。通过施加背栅电压，我们观察到〜7层MnBi ₂ Te ₄中的双极性传导和n-p转变，其中AHE电阻和纵向电阻之间的二次关系表明了其固有的AHE性质。特别是，对于～3层MnBi ₂ Te ₄ ，AHE符号可以从原始负值调整为正值。第一原理计算表明，这种 AHE 反转源于相反极化的自旋少数主导的表面态和自旋多数主导的内能带之间的竞争贝里曲率。我们的结果揭示了内在 AHE 的潜在物理机制，并为非常规符号可调 AHE 提供了新的视角。

更新日期：2023-12-18

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