Magneto-gyrotropic photogalvanic effects due to inter-subband absorption in quantum wells

TL;DR

This paper investigates the magneto-photogalvanic effect in GaAs quantum wells, revealing how inter-subband absorption under magnetic fields induces spin-related and spin-independent photocurrents, challenging traditional selection rules.

Contribution

It provides experimental evidence and theoretical analysis of MPGE due to inter-subband transitions, highlighting effects at normal incidence and proposing microscopic models.

Findings

Resonant photocurrents observed at oblique and normal incidence.

MPGE related to both spin and spin-independent processes.

Selection rules for inter-subband transitions are not strict.

Abstract

We report on the observation of the magneto-photogalvanic effect (MPGE) due to inter-subband transitions in (001)-oriented GaAs quantum wells. This effect is related to the gyrotropic properties of the structures. It is shown that inter-subband absorption of linearly polarized radiation may lead to spin-related as well as spin independent photocurrents if an external magnetic field is applied in the plane of the quantum well. The experimental results are analyzed in terms of the phenomenological theory and microscopic models of MPGE based on either asymmetric optical excitation or asymmetric relaxation of carriers in k-space. We observed resonant photocurrents not only at oblique incidence of radiation but also at normal incidence demonstrating that conventionally applied selection rules for the inter-subband optical transitions are not rigorous.