Spin-polarized tunneling into a topological Kondo insulator*

Motivated by a recent experiment [1], we propose a phenomenological model of spin-polarized tunneling of electrons into a heavy fermion Kondo lattice [2]. Specifically, we elaborate the crucial role of topological surface states that are naturally present at the interface between a topological Kondo insulator (TKI) and a normal metal, in driving a spin-selective tunneling current upon an external bias. Utilizing a self-consistent parton mean-field construction [3], we provide a qualitative description of the underlying mechanism, by focusing on the peak structure in the differential conductance. We discuss the application of this theory applied to various scanning tunneling microscope (STM) experiments where the STM tip is replaced by a TKI [4]. Unlike conventional spin-polarized STMs, the spin selectivity is voltage driven and does not depend on a magnetic tip.

[1] A. Aishwarya, et al., Science 377, 1218 (2022)

[2] M. Maltseva, M. Dzero, and P. Coleman, Phys. Rev. Lett. 103, 206402 (2009)

[3] Victor Alexandrov, Maxim Dzero, and Piers Coleman, Phys. Rev. Lett. 111, 226403 (2013)

[4] Maxim Dzero, Jing Xia, Victor Galitski, and Piers Coleman, Ann. Rev. Condens. Matter Phys. 7, 249 (2016)