Anisotropic topological magnetoelectric effect in axion insulators

Magnetoelectric polarizability and axion electrodynamics in crystalline insulators.

The orbital motion of electrons in a three-dimensional solid can generate a pseudoscalar magnetoelectric coupling theta, a fact we derive for the single-particle case using a recent theory of polarization in weakly inhomogeneous materials. This polarizability theta is the same parameter that appears in the "axion electrodynamics" Lagrangian DeltaL_{EM}=(thetae;{2}/2pih)E.B, which is known to de...

Topological magnetoelectric effect decay.

We address the influence of realistic disorder and finite doping on the effective magnetic monopole induced near the surface of an ideal topological insulator (TI) by currents that flow in response to a suddenly introduced external electric charge. We show that when the longitudinal conductivity σ(xx)=g(e(2)/h)≠0, the apparent position of a magnetic monopole initially retreats from the TI surfa...

Physics of Three-Dimensional Bosonic Topological Insulators: Surface-Deconfined Criticality and Quantized Magnetoelectric Effect

Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. The MIT Faculty has made this article openly available. Please share how this access benefits you. Your story matters. We discuss physical properties of ''integer'' topological phases of bosons in D ¼ 3 þ 1 dimensions, protected by in...

Orbital magnetoelectric coupling in band insulators

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...

Topological insulators