Transport Properties of Topological Materials

Anomalous Hall effect (AHE) as the transport manifestation of the quantum geometric properties of electron wavefunctions has been under the central focus in recent condensed matter physics. In addition to the conventional AHE probed by the magnetic field normal to the measurement plane, AHE induced by the in-plane field (in-plane AHE) has been reported in several systems[1-3], sparking interest with suggestions of novel mechanisms. By measuring a simple D_3d system, in particular, Nakamura et al. have pointed out the importance of control of the out-of-plane Berry curvature distribution or orbital magnetization by the in-plane field[3]. Observation of in-plane AHE, however, imposes strict requirements on the crystal symmetry as well as the measurement geometry, and therefore the material examples have still been quite limited. In this work, we have explored in-plane AHE in different systems, particularly focusing on topological Dirac and Weyl semimetals where the existence of Weyl points serves as giant source of Berry curvature and orbital magnetization. Through fabrication of high-quality films with appropriate crystal orientations and Hall measurements with rotating the in plane field, we demonstrate sizable in-plane AHE with characteristic field dependence appears when the field is applied in the symmetry-allowed directions.

[1] L. Wang et al., Phys. Rev. Lett. 132, 106601 (2024).

[2] W. Peng et al., arXiv:2402.15741 (2024).

[3] A. Nakamura et al., arXiv:2405.16722 (2024).