Discovery of a large magnetic nonlinear Hall effect in an altermagnet

TL;DR

This paper reports the discovery of a large, non-analytic magnetic nonlinear Hall effect in an altermagnet, revealing a quadratic Hall response dependent on magnetic field, with potential applications in high-field sensing technologies.

Contribution

It introduces the magnetic nonlinear Hall effect in an altermagnet, characterized by a quadratic dependence on magnetic field and a non-analytic reversal property, distinct from traditional Hall effects.

Findings

The MNLHE exhibits a quadratic dependence on magnetic field.

The effect is non-analytic and reverses with magnetic field direction.

It remains large and unsaturated up to 60 T, suitable for high-field sensing.

Abstract

Since Edwin Halls groundbreaking discovery of the Hall effect in 1879, magnetism, spin, and quantization have been expanding the scope of Hall effects, continuously driving transformative progress in science and technology. Among them, the latest nonlinear Hall effect (NLHE), where longitudinal electric field tunes quantum geometry to generate nonlinear Hall voltage, attracts wide attention as a sensitive probe of topological phases across a wide range of materials. Here, we report a new Hall effect member: the magnetic nonlinear Hall effect (MNLHE), characterized by a quadratic Hall conductivity dependence on magnetic field, rather than electric field as in NLHE. This finding relies on an altermagnet, Mn5Si3 thin film, whose alternating-sign Berry curvatures ensure higher-order MNLHE clearly distinguishable from the first-order anomalous Hall effect. The observed quadratic dependence originates from chiral next-nearest-neighbor hopping processes that acquire magnetic-exchange-driven Zeeman energies and Haldane-like chiral flux phases. Remarkably, this MNLHE is non-analytic, as reversing the magnetic field flips the alternating spin-splitting bands and reverses the hopping chirality, which is absent in traditional NLHE. Beyond offering a distinctive transport fingerprint for altermagnet Mn5Si3 thin film, this MNLHE is large and unsaturated up to 60 T, providing opportunities for pulsed high-field sensing technologies in both fundamental researches and engineering applications.