Anomalous anisotropic magnetoresistance in the topological semimetal HoPtBi

Discovering and understanding anomalous anisotropic magnetoresistance (AMR) effects are important aspects of studying the nature of modulated transport. The anisotropic transport coefficients of topological systems are often useful for mapping hidden phases and characterizing topological phase transitions and the evolution of topological electrons. Here, we report an unusual change in the AMR effect in HoPtBi. Remarkably, the AMR exhibits transitions from a quasi-twofold to fourfold symmetry and finally forms a stable rotated fourfold symmetry with increasing magnetic fields. The evolution analysis from the three-dimensional (3D) mapping experiments confirms that it is an intrinsic 3D effect. Fourier transformation analysis indicates that the superposition of C 2 , C 4 , and C 6 signals with phase angle transitions leads to the novel AMR. All transitions are summarized as symmetry rotation or the inversion of peaks and valleys. By combining the features of band structures and AMR, we evaluate the possible origin of this symmetry rotation and attribute it to the topological band change. This work provides insight into the anomalous AMR effect of topological materials and is useful for understanding the evolution of topological bands in a magnetic field. We propose that other rare-earth half-Heusler alloys can potentially exhibit similar phenomena.