Electromagnetic Scattering by Spheres of Topological Insulators

TL;DR

This paper systematically studies electromagnetic scattering by topological insulator spheres, revealing unconventional backward scattering due to the TME effect, antiresonances in cross-polarized scattering, and methods to measure the TME effect.

Contribution

It introduces the first detailed analysis of electromagnetic scattering properties of TI spheres, highlighting backward scattering, antiresonances, and measurement techniques for the TME effect.

Findings

Unconventional backward scattering caused by TME effect.

Antiresonances in cross-polarized scattering in Mie regime.

Quantized TME effect measurable via far-field electric fields.

Abstract

The electromagnetic scattering properties of topological insulator (TI) spheres are systematically studied in this paper. Unconventional backward scattering caused by the topological magneto-electric (TME) effect of TIs are found in both Rayleigh and Mie scattering regimes. This enhanced backward scattering can be achieved by introducing an impedance-matched background which can suppress the bulk scattering. For the cross-polarized scattering coefficients, interesting antiresonances are found in the Mie scattering regime, wherein the cross-polarized electromagnetic fields induced by the TME effect are trapped inside TI spheres. In the Rayleigh limit, the quantized TME effect of TIs can be determined by measuring the electric-field components of scattered waves in the far field.