Giant anomalous Hall conductivity in frustrated magnet EuCo2Al9

TL;DR

This study reports a giant anomalous Hall effect in a frustrated Eu-based magnet, driven by spin chirality and exchange interactions, with potential implications for spintronics.

Contribution

It reveals a giant anomalous Hall conductivity in EuCo2Al9 caused by spin chirality skew scattering and exchange splitting, advancing understanding of quantum transport in frustrated magnets.

Findings

Achieved an anomalous Hall conductivity of 31000 Ω^-1cm^-1.

Observed a giant anomalous Hall angle of 12%.

Linked the effect to spin chirality and exchange interactions.

Abstract

The interaction between conduction electrons and localized magnetic moments profoundly influences the electrical and magnetic properties of materials, giving rise to a variety of fascinating physical phenomena and quantum effects. Here, we discover a giant anomalous Hall effect (AHE) in a frustrated Eu-based magnet, exhibiting a giant anomalous Hall conductivity (AHC) of 31000 {\Omega}-1cm-1 and a remarkable anomalous Hall angle (AHA, tan{\theta}H) of 12 %--surpassing conventional mechanisms (either intrinsic or extrinsic) by two orders of magnitude. Combining magnetotransport, quantum oscillations, neutron diffraction and ab initio calculations, we establish that the giant AHC originates from fluctuating spin chirality skew scattering, generated by indirect Ruderman-Kittel-Kasuya-Yosida (RKKY) interactions of Eu-4f moments. Simultaneously, Hund's coupling of itinerant electrons and localized Eu-4f spins triggers giant exchange splitting, evidenced by temperature-dependent Fermi surface reconstruction. This work establishes a frustrated magnetic platform for engineering the AHE and elucidates the governing role of exchange interactions and spin textures in quantum transport, while also providing a framework for designing unconventional spintronic systems that harness emergent spin-texture dynamics.