Influence of the spin-orbit coupling on the Kondo effect

Wong, A., S. E. Ulloa, N. Sandler, and K. Ingersent. 2016. โ€œInfluence of the Spin-Orbit Coupling on the Kondo Effectโ€. Phys. Rev. B.

Abstract

An Anderson model for a magnetic impurity in a two-dimensional electron gas with bulk Rashba spin-orbit interaction is solved using the numerical renormalization group under two different experimental scenarios. For a fixed Fermi energy, the Kondo temperatureย ๐‘‡๐พย varies weakly with Rashba couplingย ๐œ†๐‘…, as reported previously. If instead the band filling is low and held constant, increasingย ๐œ†๐‘…ย can drive the system into a helical regime with exponential enhancement ofย ๐‘‡๐พ. Under either scenario, thermodynamic properties at low temperaturesย ๐‘‡ย exhibit the same dependencies onย ๐‘‡/๐‘‡๐พย as are found forย ๐œ†๐‘…=0. Unlike the conventional Kondo effect, however, the impurity exhibits static spin correlations with conduction electrons of nonzero orbital angular momentum about the impurity site. We also consider a magnetic field that Zeeman splits the conduction band but not the impurity level, an effective picture that arises under a proposed route to access the helical regime in a driven system. The impurity contribution to the system's ground-state angular momentum is found to be a universal function of the ratio of the Zeeman energy to a temperature scale that is notย ๐‘‡๐พย (as would be the case in a magnetic field that couples directly to the impurity spin), but rather is proportional toย ๐‘‡๐พย divided by the impurity hybridization width. This universal scaling is explained via a perturbative treatment of field-induced changes in the electronic density of states.

Last updated on 09/21/2024