Extremely Large Anomalous Hall Conductivity and Unusual Axial Diamagnetism in a Quasi-1D Dirac Material La₃MgBi₅.

Abstract

Anomalous Hall effect (AHE), one of the most important electronic transport phenomena, generally appears in ferromagnetic materials but is rare in materials without magnetic elements. Here, a study of La₃MgBi₅ is presented, whose band structure carries multitype Dirac fermions. Although magnetic elements are absent in La₃MgBi₅, the signals of AHE can be observed. In particular, the anomalous Hall conductivity is extremely large, reaching 42,356 Ω^-1 cm^-1 with an anomalous Hall angle of 8.8%, the largest one that has been observed in the current AHE systems. The AHE is suggested to originate from the combination of skew scattering and Berry curvature. Another unique property discovered in La₃MgBi₅ is the axial diamagnetism. The diamagnetism is significantly enhanced and dominates the magnetization in the axial directions, which is the result of the restricted motion of the Dirac fermion at the Fermi level. These findings not only establish La₃MgBi₅ as a suitable platform to study AHE and quantum transport but also indicate the great potential of 315-type Bi-based materials for exploring novel physical properties.