RKKY interaction in a disordered two-dimensional electron gas with Rashba and Dresselhaus spin-orbit couplings

TL;DR

This paper provides a theoretical analysis of the RKKY interaction in a disordered 2D electron gas with Rashba and Dresselhaus spin-orbit couplings, revealing how disorder and spin-orbit effects influence magnetic interactions.

Contribution

It offers analytical and numerical insights into the disorder-averaged RKKY interaction and its fluctuations in systems with combined Rashba and Dresselhaus couplings, including limiting cases.

Findings

Disorder suppresses the average RKKY interaction exponentially with distance.

Fluctuations of the RKKY interaction decay with the same power-law as in clean systems.

Analytic expressions are derived for large/small spin-orbit interactions and equal Rashba and Dresselhaus couplings.

Abstract

We study theoretically the statistical properties of the Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction between localized magnetic moments in a disordered two-dimensional electron gas with both Rashba and Dresselhaus spin-orbit couplings. Averaging over disorder, the static spin susceptibility tensor is evaluated diagrammatically in the mesoscopic (phase-coherent) regime. The disorder-averaged susceptibility leads to a twisted exchange interaction suppressed exponentially with distance, whereas the second-order correlations, which determine the fluctuations (variance) of the RKKY energy, decay with the same power-law as in the clean case. We obtain analytic expressions in the limits of large/small spin orbit interactions and for equal Rashba and Dresselhaus couplings. Beside these limiting cases, we study numerically the variance of the RKKY interaction in the presence of pure Rashba spin-orbit coupling. Our results are relevant for magnetic impurities or nuclear moments embedded in III-V two-dimensional heterostructures or in contact with surface states of metals and metal alloys, which can display a sizable Rashba spin-orbit coupling.