Facet-dependent Electronic Quantum Diffusion in the High-Order Topological Insulator Bi4Br4

We apply the magnetoconductivity characteristic and angle-resolved photoemission spectroscopy (ARPES) to visualize the evolution of surface-selected electronic features of quasi-one-dimensional material Bi4Br4. The transport measurements indicate the quantum-interference correction to conductivity possesses a symbolic spin-rotational characteristic correlated to the value of Berry phase with the effects of weak localization and weak antilocalization for (001) and (100) surfaces, respectively. The ARPES spectra provide the experimental evidence for a quasi-one-dimensional surface state at the side (100) surface and an anisotropic massive Dirac surface state at the top (001) surface, respectively, which is highly coincided with the angle-dependent scaling behavior of magnetoconductivity. Our results reveal the facet-dependent electronic quantum diffusion in quasi-one-dimensional Bi4Br4, stimulating further investigations of this topological class and applications of the feasible technologies of topological spintronics.