Third-order charge transport in a magnetic topological semimetal

TL;DR

This paper investigates third-order nonlinear charge transport in a magnetic topological semimetal, revealing how topological features influence nonlinear responses and can serve as sensitive probes of phase transitions.

Contribution

It demonstrates the impact of topological band crossings on third-order charge transport in an antiferromagnetic semimetal, highlighting the sensitivity of nonlinear responses to topological phase changes.

Findings

Third-order current response dominates transverse charge transport.

Nonlinear response is highly sensitive to topological phase transitions.

Topological features produce large Berry connection polarizability.

Abstract

Magnetic topological materials and their physical signatures are a focus of current research. Here, by first-principles calculations and symmetry analysis, we reveal topological semimetal states in an existing antiferromagnet ThMn2Si2. Depending on the N\'eel vector orientation, the topological band crossings near the Fermi level form either a double-nodal loop or two pairs of Dirac points,which are all fourfold degenerate and robust under spin-orbit coupling. These topological features produce large Berry connection polarizability, which leads to enhanced nonlinear transport effects. Particularly, we evaluate the third order current response, which dominates the transverse charge current. We show that the nonlinear response can be much more sensitive to topological phase transitions than linear response, which offers a powerful tool for characterizing magnetic topological semimetals.