Nonperturbative Magnetic Orbital Hall Effect in Altermagnets

TL;DR

This paper uncovers a giant, nonperturbative magnetic orbital Hall effect in altermagnets, which is symmetry-allowed and can be manipulated without external fields, with potential for high-performance memory applications.

Contribution

It demonstrates the existence of a nonperturbative magnetic orbital Hall effect in altermagnets, expanding understanding of their orbital transport phenomena beyond spin-orbit coupling dependence.

Findings

The magnetic orbital Hall effect is forbidden in collinear antiferromagnets but allowed in all altermagnet classes.

The effect reaches giant magnitudes, comparable to or exceeding the spin Hall effect.

First-principles calculations predict strong room-temperature responses in CrSb and FeSb2.

Abstract

Recent studies on altermagnets have focused considerable attention on nonrelativistic effects that persist in the absence of spin-orbit coupling (SOC). As a result, the relative importance of various phenomena in altermagnets has commonly been judged by their dependence on SOC. Here, we challenge this common wisdom by uncovering the magnetic orbital Hall effect, which is nonperturbative in SOC strength. We establish the symmetry properties of this effect, demonstrating that it is strictly forbidden in conventional collinear antiferromagnets yet universally allowed in all ten spin-Laue classes of collinear altermagnets. Counterintuitively, although SOC-induced, it reaches giant magnitudes in altermagnets-comparable to or even exceeding the nonrelativistic spin Hall effect. Moreover, altermagnetic symmetry enables unconventional collinear-polarized orbital currents, allowing field-free manipulation of perpendicular magnetization. Our first-principles calculations predict strong room-temperature responses in the experimentally established altermagnets CrSb and FeSb2. These findings reveal the previously overlooked potential of altermagnetic orbitronics and broaden the horizons for altermagnets in high-performance magnetic memory applications.