Gyrotropy and magneto-spatial dispersion effects at intersubband transitions in quantum wells

TL;DR

This paper provides a theoretical analysis of gyrotropic and magneto-spatial dispersion effects in quantum wells, revealing their spectral characteristics and experimental detectability, based on symmetry, phenomenological, and microscopic models.

Contribution

It introduces a comprehensive theoretical framework for understanding gyrotropy and magneto-spatial dispersion in quantum wells, including symmetry analysis and microscopic modeling.

Findings

Gyrotropy and magneto-spatial dispersion constants show asymmetrical spectral peaks.

Effects are detectable in experiments based on estimated magnitudes.

Angular dependences of optical signals are established for different growth directions.

Abstract

Gyrotropic properties of multiple quantum well structures are studied theoretically. Symmetry analysis is performed yielding the gyrotropy tensor components for structures grown along [001], [110] and [311] crystallographic directions. Angular dependences of circular dichroism and natural optical activity signals are established. Phenomenological model and microscopic theory based on spin-orbit splitting of size-quantized subbands are developed for photon energies close to the energy of the intersubband optical transition. Magneto-spatial dispersion effects arising from the diamagnetic shift of the intersubband energy gap linear in the electron momentum are also considered. It is demonstrated that the spectral dependence of the gyrotropy and magneto-spatial dispersion constants represents an asymmetrical peak with a degree of asymmetry governed by the mean electron energy. The estimates show that the considered effects are detectable in experiments.