# Time-reversal-symmetric topological magnetoelectric effect in three-dimensional topological insulators

## TL;DR

This paper explores a novel time-reversal-symmetric topological magnetoelectric effect in three-dimensional topological insulators, where the electric charge depends solely on the magnetic field's magnitude, not its direction.

## Contribution

It introduces a nonperturbative theoretical framework for a time-reversal-symmetric TME and proposes an experimental setup to observe this effect.

## Key findings

- Electric charge depends only on magnetic field magnitude
- The effect is independent of magnetic field sign
- Proposed mesoscopic experimental demonstration

## Abstract

One of the hallmarks of time-reversal-symmetric topological insulators in three dimensions is the topological magnetoelectric effect (TME). So far, a time-reversal breaking variant of this effect has attracted much attention, in the sense that the induced electric charge changes sign when the direction of an externally applied magnetic field is reversed. Theoretically, this effect is described by the so-called axion term. Here, we discuss a time-reversal-symmetric TME, where the electric charge depends only on the magnitude of the magnetic field but is independent of its sign. We obtain this nonperturbative result by a combination of analytic and numerical arguments, and suggest a mesoscopic setup to demonstrate it experimentally.