A magnetic field parallel to the current in topological semimetals can induce chiral anomaly, which in turn triggers the planar Hall effect (PHE) - a characteristic regarded as a key transport signature for identifying topological semimetals. As a non-magnetic type-I Weyl semimetal, trigonal PtBi₂ is inherently free from the interference of anisotropic magnetic scattering, and its chiral anomaly is independent of current direction. Furthermore, its complex electronic structure endows the material’s anisotropic magnetoresistance (AMR) and PHE with high-order features which are sensitive to current orientation, making it an ideal research system for investigating the effect of current direction on magnetotransport properties.
In this work, high-quality layered single crystals of trigonal PtBi₂ were prepared via the self-flux method, and systematic electrical and magnetic transport measurements were conducted on the crystals. Meanwhile, first-principles calculations based on density functional theory (DFT) were performed using the Vienna Ab initio Simulation Package (VASP) to simulate the AMR with current along the b-axis, which theoretically ruled out the interference of extrinsic factors on the anisotropic magnetotransport signals.
Experimental results show that the a-axis and b-axis of PtBi₂ exhibit obvious high-order features in both AMR and PHE. The fitting results of AMR and PHE show that the symmetry of the b-axis is lower than that of the a-axis. Further analysis showed that the angles corresponding to the extreme values of AMR and PHE depend on the angle between the magnetic field and the lattice. This phenomenon is closely related to the unique configuration of the PtBi₂ Fermi surface, which means the potential impact of Fermi surface symmetry on magnetic transport properties. In addition, the AMR when the current flows along the b-axis was calculated through first-principles calculations. The results show that the peak under high magnetic field is obviously sharp and there are slight ridges on both sides, while the curve under low magnetic field is overall smooth. These characteristics are in good agreement with the experimental data, verifying that the observed magnetic transport characteristics are the intrinsic characteristics of trigonal PtBi₂.
This work reveals the effect of current direction on the in-plane magnetic transport properties of PtBi₂ and demonstrates the close correlation between the Fermi surface configuration and the angular dependence of magnetoresistance. It thus provides experimental and theoretical evidence for understanding the physical mechanism of anisotropic magnetotransport in Weyl semimetals and enriches the research on the transport characteristics of topological semimetals.