Resonant Subband Landau Level Coupling in Symmetric Quantum Well

TL;DR

This study investigates the subband structure and Landau level coupling in a high-mobility GaAs/AlGaAs quantum well using magneto-infrared spectroscopy, revealing multiple resonant couplings and a forbidden transition, and confirming the depolarization shift with a semiclassical model.

Contribution

It provides detailed experimental identification of resonant subband Landau level couplings and a forbidden transition, along with a theoretical explanation of depolarization shifts in symmetric quantum wells.

Findings

Resonant couplings between the 1st and up to the 4th subbands were identified.

A forbidden intersubband transition (1st to 3rd) was observed.

Depolarization shift is well described by the semiclassical slab plasma model.

Abstract

Subband structure and depolarization shifts in an ultra-high mobility GaAs/Al_{0.24}Ga_{0.76}As quantum well are studied using magneto-infrared spectroscopy via resonant subband Landau level coupling. Resonant couplings between the 1st and up to the 4th subbands are identified by well-separated anti-level-crossing split resonance, while the hy-lying subbands were identified by the cyclotron resonance linewidth broadening in the literature. In addition, a forbidden intersubband transition (1st to 3rd) has been observed. With the precise determination of the subband structure, we find that the depolarization shift can be well described by the semiclassical slab plasma model, and the possible origins for the forbidden transition are discussed.