Magnetoelectric effect in cylindrical topological insulators

TL;DR

This paper models the electromagnetic response of cylindrical topological insulators, revealing unique magnetoelectric effects including magnetic monopole-like fields, and proposes experimental setups for their detection.

Contribution

It constructs a Green's function for cylindrical TIs, enabling analysis of their EM response and predicting magnetic monopole phenomena near the surface.

Findings

Magnetic monopole-like charge and current densities appear near the TI surface.

Green's function formalism describes EM response of cylindrical TIs.

Proposed experimental setups to detect magnetic monopole fields.

Abstract

Topological insulators (TIs) exhibit a quantized magnetoelectric response when time-reversal symmetry is broken on its surface. This unusual electromagnetic (EM) response is a unique macroscopic manifestation of the quantum Hall effect on the TI surface and it is described by a quantized Chern-Simons theory. In this paper, we construct the Green's function (GF) describing the EM response of two topological media separated by a cylindrical interface. This GF, in the appropriate limits, describes the magnetoelectric effect of both i) a cylindrical TI surrounded by a dielectric fluid, and ii) a TI with a cylindrical dielectric-filled cavity. We calculate the EM fields produced by a line charge and a line current near the TI surface and we show that, in addition to the standard image electromagnetic sources, charge and current densities of magnetic monopoles will also appear. We discuss some experimental setups which could be used to test these magnetic monopole fields.