Orbital magnetoelectric coupling in band insulators

Article

关键词: DENSITY-MATRIX;    WANNIER FUNCTIONS;    POLARIZATION;    INVARIANCE;    ELECTRON;    CRYSTALS;    FIELD;   

DOI  :  10.1103/PhysRevB.81.205104

来源: SCIE

【 摘 要 】

Magnetoelectric responses are a fundamental characteristic of materials that break time-reversal and inversion symmetries (notably multiferroics) and, remarkably, of topological insulators in which those symmetries are unbroken. Previous work has shown how to compute spin and lattice contributions to the magnetoelectric tensor. Here we solve the problem of orbital contributions by computing the frozen-lattice electronic polarization induced by a magnetic field. One part of this response (the Chern-Simons term) can appear even in time-reversal-symmetric materials and has been previously shown to be quantized in topological insulators. In general materials there are additional orbital contributions to all parts of the magnetoelectric tensor; these vanish in topological insulators by symmetry and also vanish in several simplified models without time reversal and inversion whose magnetoelectric couplings were studied before. We give two derivations of the response formula, one based on a uniform magnetic field and one based on extrapolation of a long-wavelength magnetic field, and discuss some of the consequences of this formula.

【 授权许可】

Free