Anomalous response in the orbital magnetic susceptibility of 2D topological systems

TL;DR

This paper reveals a singular behavior in the orbital magnetic susceptibility of 2D topological materials, showing how topological regimes exhibit enhanced responses due to a k-dependent mass term, with implications for magnetic property manipulation.

Contribution

It introduces a k-dependent mass term in the relativistic formalism to distinguish topological trivial and non-trivial regimes, unveiling a singular susceptibility contribution in non-trivial phases.

Findings

Non-trivial topological regimes show a susceptibility inversely proportional to the square of magnetic flux.

A new method to enhance orbital magnetism without small band gaps.

Identification of measurement conditions for observing the anomalous response.

Abstract

Two-dimensional compounds with non-zero Berry curvature are ideal systems to study exotic and technologically favourable thermoelectric and magnetoelectric properties. Within this class of materials, the topological trivial and non-trivial regimes had to present very different behaviours which are encoded for the orbital susceptibility and magnetization. In order to try to reveal them, we have found that it was necessary to introduce a k-dependent mass term in the relativistic formalism of these materials. Thus, while a topologically trivial insulator is predicted to have a very limited response, in the non-trivial regime we unveil a singular contribution to the orbital magnetic susceptibility which is inversely proportional to the square of the quantum magnetic flux. In this emergent scenario, besides determining the measurement conditions we also find a new route for enhancing the intrinsic orbital magnetism of topological materials widening the range of temperatures and magnetic fields without involving tiny band gaps.