Anisotropic splitting of intersubband spin plasmons in quantum wells with bulk and structural inversion asymmetry

TL;DR

This paper investigates how bulk and structural inversion asymmetry affect the anisotropic splitting of intersubband spin plasmons in quantum wells, revealing a three-fold dispersion splitting influenced by spin-orbit coupling.

Contribution

It introduces a theoretical analysis of anisotropic spin plasmon splitting in asymmetric quantum wells, highlighting the role of inversion asymmetry and many-body effects.

Findings

Predicted a three-fold anisotropic splitting of spin plasmon dispersion.

Found that crystal magnetic fields do not cause decoherence of collective spin excitations.

Discussed conditions for experimental detection via inelastic light scattering.

Abstract

In semiconductor heterostructures, bulk and structural inversion asymmetry and spin-orbit coupling induce a k-dependent spin splitting of valence and conduction subbands, which can be viewed as being caused by momentum-dependent crystal magnetic fields. This paper studies the influence of these effective magnetic fields on the intersubband spin dynamics in an asymmetric n-type GaAs/AlGaAs quantum well. We calculate the dispersions of intersubband spin plasmons using linear response theory. The so-called D'yakonov-Perel' decoherence mechanism is inactive for collective intersubband excitations, i.e., crystal magnetic fields do not lead to decoherence of spin plasmons. Instead, we predict that the main signature of bulk and structural inversion asymmetry in intersubband spin dynamics is a three-fold, anisotropic splitting of the spin plasmon dispersion. The importance of many-body effects is pointed out, and conditions for experimental observation with inelastic light scattering are discussed.