Observation of magnetically switchable quantum geometric photocurrents

TL;DR

This study experimentally demonstrates magnetically switchable quantum geometric photocurrents in a van der Waals antiferromagnet, revealing new ways to control photocurrents via magnetic order for spintronics and light harvesting.

Contribution

First experimental observation of magnetically switchable quantum geometric photocurrents, confirming theoretical predictions about their dependence on magnetic order and light polarization.

Findings

Demonstrated switching of photocurrents by flipping the Nél vector.

Confirmed frequency and temperature dependence consistent with theoretical assignments.

Identified new magnetically controllable photocurrents related to quantum geometry.

Abstract

In non-centrosymmetric materials, light can be rectified into two types of DC photocurrents, known as injection and shift currents, through the bulk photovoltaic effect. Recent theory has uncovered their deep relation with the two-state quantum geometry of resonant transitions: In non-magnetic crystals, where these currents have been routinely observed, the injection current responds to circular light and probes the Berry curvature, while the shift current responds to linear light and probes the geometric connection. Magnetic crystals have been predicted to show a new set of hitherto unobserved magnetically switchable photocurrents, with the roles of linear and circular light interchanged: A linear injection current, which probes the quantum metric, and a circular shift current, which probes the geometric torsion. In this work, we demonstrate the existence of such currents for the first time, demonstrating the switching of the current by flipping the N\'eel vector in a van der Waals antiferromagnet. Furthermore, their specific frequency and temperature dependence confirm the assignment of circular shift and linear injection currents. Our work demonstrates a new way to control photocurrents in magnets that are directly tied to geometry and have promising applications in antiferromagnetic spintronics and light harvesting.