RIKEN Center for Emergent Matter Science (CEMS), Wako, Saitama, 351-0198, Japan.
Department of Applied Physics, University of Tokyo, Tokyo, 113-8656, Japan.
Nat Commun. 2018 Sep 14;9(1):3740. doi: 10.1038/s41467-018-05759-4.
Directional transport and propagation of quantum particle and current, such as electron, photon, spin, and phonon, are known to occur in the materials system with broken inversion symmetry, as exemplified by the diode in semiconductor p-n junction and the natural optical activity in chiral materials. Such a nonreciprocal response in the quantum materials of noncentrosymmetry occurs ubiquitously when the time-reversal symmetry is further broken by applying a magnetic field or with spontaneous magnetization, such as the magnetochiral effect and the nonreciprocal magnon transport or spin current in chiral magnets. In the nonlinear regime responding to the square of current and electric field, even a more variety of nonreciprocal phenomena can show up, including the photocurrent of topological origin and the unidirectional magnetoresistance in polar/chiral semiconductors. Microscopically, these nonreciprocal responses in the quantum materials are frequently encoded by the quantum Berry phase, the toroidal moment, and the magnetoelectric monopole, thus cultivating the fertile ground of the functional topological materials. Here, we review the basic mechanisms and emergent phenomena and functions of the nonreciprocal responses in the noncentrosymmetric quantum materials.
量子粒子和电流（如电子、光子、自旋和声子）的定向输运和传播已知发生在具有非中心对称破缺的材料系统中，例如半导体 p-n 结中的二极管和手性材料中的自然旋光性。当时间反演对称性通过施加磁场或自发磁化进一步被打破时，这种非中心对称量子材料中的非互易响应普遍存在，例如磁手性效应和手性磁体中的非互易磁子输运或自旋电流。在响应电流和电场平方的非线性 regime 中，甚至会出现更多种类的非互易现象，包括拓扑起源的光电流和极性/手性半导体中的单向磁阻。从微观上看，这些量子材料中的非互易响应通常由量子 Berry 相位、环形矩和磁电单极子编码，从而为功能拓扑材料培育了肥沃的土壤。在这里，我们回顾了非中心对称量子材料中非互易响应的基本机制和涌现现象及其功能。
