Effects of interaction on field-induced resonances in confined Fermi liquid

TL;DR

This paper investigates how weak interactions affect the ballistic spin resonance in a confined two-dimensional electron gas, revealing a shift in resonance conditions due to the absence of Kohn theorem for spin modes.

Contribution

It demonstrates that weak short-range interactions shift the Zeeman splitting at which spin polarization minima occur, due to the non-applicability of Kohn theorem to spin collective modes.

Findings

Resonance persists under weak interactions

Interaction causes a shift in the resonance condition

Absence of Kohn theorem explains the shift

Abstract

We consider the two-dimensional electron gas confined laterally to a narrow channel by a harmonic potential. As the Zeeman splitting matches the intersubband separation the nonlocal spin polarization develops a minimum as reported by Frolov et al. [Nature (London) 458, 868 (2009)]. This phenomenon termed Ballistic Spin Resonance is due to the degeneracy between the nearest oppositely polarized subbands that is lifted by spin-orbit coupling. We showed that the resonance survives the weak and short-range interaction. The latter detunes it and as a result shifts the Zeeman splitting at which the minimum in spin polarization occurs. Here this shift is attributed to the absence of Kohn theorem for the spin sloshing collective mode. We characterized the shift due to weak interaction qualitatively by analyzing the spin sloshing mode within the Fermi liquid phenomenology.