Spin-polarized STM study of topological magnet and quantum impurity*

We have developed vector magnetic field based scanning tunneling microscopy/spectroscopy (STM/S) technique to probe and discover topological magnets [1-2]. Here we report spin-polarized STM/S to study of the engineered quantum impurity in a topological magnet Co₃Sn₂S₂ [2]. We find that each substituted In impurity introduces a striking localized bound state. Our systematic magnetization-polarized probe reveals that this bound state is spin-down polarized, in lock with a negative orbital magnetization. Moreover, the magnetic bound states of neighboring impurities interact to form quantized orbitals, exhibiting an intriguing spin-orbit splitting, analogous to the splitting of the topological fermion line. Our work collectively demonstrates the strong spin-orbit effect of the single-atomic impurity at the quantum level, suggesting that a nonmagnetic impurity can introduce spin-orbit coupled magnetic resonance in topological magnets.

1. J-X Yin, S S Zhang et al. Nature Physics 15, 443 (2019).
2. J-X Yin, N Shumiya et al. Nat Commun 11, 4415 (2020).