Resonant exchange interaction in semiconductors

TL;DR

This paper introduces a non-perturbative method to calculate the resonant exchange interaction between paramagnetic impurities in semiconductors, revealing significant enhancement when impurity bound states align with free carrier energies.

Contribution

It develops a new non-perturbative approach that accounts for impurity bound states, showing how resonant tunneling can greatly amplify exchange interactions in 2D semiconductor systems.

Findings

Resonant tunneling significantly enhances exchange interaction

Bound state energy alignment with free carriers increases interaction strength

Interaction exceeds conventional RKKY estimates by orders of magnitude

Abstract

We present a non-perturbative calculation of indirect exchange interaction between two paramagnetic impurities via 2D free carriers gas separated by a tunnel barrier. The new method accounts for the impurity attractive potential producing a bound state. The calculations show that for if the bound impurity state energy lies within the energy range occupied by the free 2D carriers the indirect exchange interaction is strongly enhanced due to resonant tunneling and exceeds by a few orders of magnitude what one would expect from the conventional RKKY approach.