Kondo effect in monolayer transition metal dichalcogenide Ising superconductors

Abstract

Many recent studies show that the hole-doped monolayer transition metal dichalcogenides (TMDs) exhibit Ising superconductivity. The Ising-type spin-orbit coupling (SOC) results in spin-momentum locking perpendicular to the two-dimensional crystal near the $K$ and $\ensuremath{-}K$ valleys, strongly protecting the superconducting state against in-plane magnetic fields. In this work, we theoretically study the Kondo effect of a magnetic impurity doped in monolayer TMDs with the Ising SOC protected superconducting state. Based on behaviors of spin-induced Yu-Shiba-Rusinov bound states and localized magnetic susceptibility, we show that the Ising SOC plays an important role in enhancing or suppressing the Kondo screening of the magnetic impurity, depending on the relative position of the Fermi level with respect to the Ising splitting. More importantly, the Ising SOC exhibits opposite influences on the quantum phase transition between magnetic doublet and Kondo singlet ground states in electron- and hole-doped cases. These features in Kondo screening can be tuned by ionic liquid-gating in experiments.