Spectroscopic origin of giant anomalous Hall effect in an interwoven magnetic kagome metal

TL;DR

This paper uncovers the spectroscopic mechanisms behind the giant anomalous Hall effect in a specially designed magnetic kagome metal, TbTi$_3$Bi$_4$, revealing strong electron-magnetic coupling and novel magnetic orders.

Contribution

It introduces a new design strategy for kagome-lattice materials with emergent magnetism, demonstrating a record-high anomalous Hall conductivity and spectroscopic insights into its origin.

Findings

Record-high anomalous Hall conductivity of 10^5 Ω^{-1} cm^{-1}

Observation of large band folding gap via ARPES

Detection of spin-density-wave order and spiral magnetic order

Abstract

The discovery of a giant anomalous Hall effect (AHE) and its novel mechanism holds significant promise for advancing both fundamental research and practical applications. Magnetic kagome lattice materials are uniquely suited for studying the AHE due to their interplay between electronic structure, topology, and magnetism. However, the geometric frustration inherent in kagome lattices often limits the configuration and tunability of magnetic order. Here, we present a new design strategy for kagome-lattice materials with emergent magnetism, exemplified by the magnetic kagome metal TbTi$_3$Bi$_4$, which features interwoven magnetic Tb zigzag chains and non-magnetic Ti kagome bilayers. This material exhibits a record-high anomalous Hall conductivity (AHC) of 10$^5$ $\Omega^{-1}$ cm$^{-1}$. Spectroscopy measurements reveal a large band folding gap observed via angle-resolved photoemission spectroscopy, coexisting spin-density-wave (SDW) order detected through spin-polarized scanning tunneling spectroscopy, and a spiral magnetic order with large magnetic moments identified by neutron diffraction. These findings highlight a strong electron-magnetic coupling between itinerant charges and ordered magnetic moments, offering a spectroscopic explanation for the giant AHC in TbTi$_3$Bi$_4$. This work establishes a pathway for innovative material design strategies, unlocking new possibilities for future exploration and applications in quantum and spintronic technologies.