RKKY interaction and intervalley processes in p-doped transition metal dichalcogenides

TL;DR

This paper investigates the RKKY interaction in p-doped transition metal dichalcogenides, revealing how valley processes and lattice symmetry influence magnetic impurity interactions, with implications for experimental control and observation.

Contribution

It introduces a detailed analysis of RKKY interactions considering valley and lattice effects in p-doped TMDs, highlighting the role of the $ ext{Γ}$ valley and angular dependence.

Findings

Valence band valleys significantly enhance RKKY interaction.

Complex oscillation patterns arise from inter-valley scattering.

Doping controls the interaction symmetry and strength.

Abstract

We study the Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction in p-doped transition metal dichalcogenides such as MoS$_2$ and WS$_2$. We consider magnetic impurities hybridized to the Mo d-orbitals characteristic of the valence bands. Using the Matsubara Green's function formalism, we obtain the two-impurity interaction vs their separation and chemical potential of the system, accounting for the important angular dependence which reflects the underlying triangular lattice symmetry. The inclusion of the valence band valley at the $\Gamma$ point results in a strong enhancement of the interaction. Electron scattering processes transferring momentum between valleys at different symmetry points give rise to complex spatial oscillation patterns. Variable doping would allow the exploration of rather interesting behavior in the interaction of magnetic impurities on the surfaces of these materials, including the control of the interaction symmetry, which can be directly probed in STM experiments.