物理
拓扑绝缘体
量化(信号处理)
凝聚态物理
奇偶性(物理)
量子霍尔效应
量子力学
量子反常霍尔效应
磁场
朗道量子化
T对称
迪拉克费米子
拓扑(电路)
费米子
超导电性
组合数学
计算机科学
数学
计算机视觉
作者
Masataka Mogi,Y. Okamura,Minoru Kawamura,Ryutaro Yoshimi,K. Yasuda,Atsushi Tsukazaki,Kei Takahashi,Takahiro Morimoto,Naoto Nagaosa,Masashi Kawasaki,Y. Takahashi,Y. Tokura
出处
期刊:Nature Physics
[Springer Nature]
日期:2022-01-27
卷期号:18 (4): 390-394
被引量:44
标识
DOI:10.1038/s41567-021-01490-y
摘要
A three-dimensional topological insulator features a two-dimensional surface state consisting of a single linearly-dispersive Dirac cone. Under broken time-reversal symmetry, the single Dirac cone is predicted to cause half-integer quantization of Hall conductance, which is a manifestation of the parity anomaly in quantum field theory. However, despite various observations of quantization phenomena, the half-integer quantization has been elusive because a pair of equivalent Dirac cones on two opposing surfaces are simultaneously measured in ordinary experiments. Here we demonstrate the half-integer quantization of Hall conductance in a synthetic heterostructure termed a 'semi-magnetic' topological insulator, where only one surface state is gapped by magnetic doping and the opposite one is non-magnetic and gapless. We observe half quantized Faraday/Kerr rotations with terahertz magneto-optical spectroscopy and half quantized Hall conductance in transport at zero magnetic field. Our results suggest a condensed-matter realization of the parity anomaly and open a way for studying unconventional physics enabled by a single Dirac fermion.
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