Geometrically induced reversion of Hall current in a topological insulator cavity

TL;DR

This paper demonstrates that the curvature of a topological insulator surface can induce a reversal in the Hall current, with potential experimental implications for curved geometries like semispherical and semicylindrical cavities.

Contribution

It reveals how negative curvature surfaces can invert Hall current direction in topological insulators, linking geometry with electromagnetic response.

Findings

Hall current reverses in semispherical cavities when charge crosses focus

Reversal is equivalent to inverting the image magnetic monopole charge

Feasibility of observing effects in semicylindrical cavities in experiments

Abstract

An electric charge near the surface of a topological insulator induces an image magnetic monopole. Here, we show that if the topological insulator surface has a negative curvature, namely in the case of a semispherical cavity, the induced Hall current reverses its rotation as the electric charge crosses the semisphere geometric focus. Such a reversion is shown to be equivalent of inverting the charge of the image magnetic monopole. We also discuss upon the case of a semicylindrical cavity, where Hall current reversion appears to be feasible of probing in realistic experiments.