Angle dependent quantum phase transition from quantum anomalous insulator to axion insulator

Axion insulators, manifested by their distinct topological surface states and the implication for axion physics in low energy condensed matter systems, have been realized within heterostructures comprising magnetic topological insulators. These materials exhibit an exotic zero Hall plateau effect, resulting from opposite magnetization induced by different magnetic ion dopant species on their top and bottom surfaces. While the transition between Chern insulators and axion insulators can be readily achieved by modulating the magnetic field in the out-of-plane direction, the response of axion insulators to in-plane magnetic fields remains elusive.

In this study, we investigate the unexplored properties of Cr- and V- doped (Bi,Sb)₂Te₃ under the influence of in-plane magnetic fields and the angle-dependent magnetic field configurations. Transport behavior during quantum phase transitions is systematically investigated. Our findings shed light on the intricate interplay between magnetic field orientation and the topological surface states of axion insulators, providing valuable insights into the potential control and manipulation of these materials for applications in novel electronic and quantum technologies.