在时间逆向对称条件下观察非线性霍尔效应
Qiong Ma1, Su-Yang Xu1, Huitao Shen1
1Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, USA.
Nature
|December 19, 2018
概括
研究人员在没有磁场的非磁性WTe2双层中观察到非线性霍尔效应. 这种新奇的效应与异常的霍尔效应不同, 提供了检测量子材料中的贝里曲率的新方法.
科学领域:
- 凝聚物质物理学
- 量子材料科学
- 电传输现象
背景情况:
- 霍尔效应对于发现拓不变量至关重要,通常需要磁场.
- 异常的霍尔效应发生在没有外部场的磁性材料中.
- 时间逆向对称性通常防止在零磁场下的非磁性材料的霍尔效应.
研究的目的:
- 在时间逆向对称条件下研究非磁性材料的非线性霍尔效应.
- 探索量子材料中超越线性反应的电传输现象.
- 通过非线性电流检测贝里曲线的新方法.
主要方法:
- 在双层二甲 (WTe2) 中对电传输的实验观测.
- 应用电流和测量横向和纵向电压.
- 在非线性响应模式下分析电流电压特征.
主要成果:
- 即使没有磁场,也观察到双层WTe2中的非线性霍尔电压.
- 证明了正方位电流电压关系,与异常霍尔效应的线性特征不同.
- 测量了一个大的横向电压响应,导致一个非线性霍尔角接近90度.
- 展示了非线性霍尔效应作为贝里曲率双极时刻的直接探测.
结论:
- 非线性霍尔效应在反向时间对称的非磁性量子材料 (WTe2) 中被证明.
- 与异常的霍尔效应相比,这种效应具有不同的特性,包括二次性IV特性.
- 非线性霍尔效应为检测材料中的贝里曲率提供了一种新而敏感的方法.
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