Magnetotransport Spectroscopy of Strongly Rashba-Split Hole Subbands Reveals Many-Body Interactions

TL;DR

This study uses magnetotransport spectroscopy on 2D hole gases in GaAs/AlGaAs heterojunctions to reveal many-body interaction effects on spin-orbit-split heavy-hole subbands, showing mass enhancements and resolving discrepancies in effective mass measurements.

Contribution

It provides a detailed analysis of heavy-hole subband effective masses, demonstrating many-body interaction effects and reconciling different measurement techniques in GaAs systems.

Findings

Both heavy-hole subband masses are enhanced by a factor of about 2.3 due to many-body interactions.

The lighter heavy-hole subband exhibits a parabolic dispersion below the band anticrossing.

The study reconciles discrepancies between Luttinger theory, magnetotransport, and cyclotron resonance measurements.

Abstract

We report the results of magnetotransport experiments carried out on low-disorder 2D hole gases (2DHG) in the strongly correlated liquid regime, hosted in dopant-free (100) GaAs/AlGaAs single heterojunctions. Over a wide range of 2DHG densities (from 0.7 $\times$ 10$^{15}$/m$^2$ to $2 \times 10^{15}$/m$^2$), Fourier analysis of low-field (B < 1 T) Shubnikov-de Haas oscillations reveals two spin-orbit-split heavy-hole (HH) subbands with distinct effective masses contributing to transport. Surprisingly, the lighter-mass HH subband exhibits a parabolic dispersion with Fermi wavevector below the anticrossing between the heavy-hole and light-hole subbands, while the heavier HH subband is non-parabolic throughout. Quantitative comparison with numerical calculations based on the Luttinger model reveals that both effective masses are enhanced by a common factor ($\approx$ 2.3), which we attribute to many-body interactions. This common scaling factor has a very weak dependence on the 2DHG density, likely due to band hybridization. Our measured hole masses are compared with published cyclotron resonance and magnetotransport values. We propose a cohesive framework reconciling the long-standing three-way discrepancy between Luttinger theory, magnetotransport, and cyclotron resonance measurements of density-dependent effective masses in partially spin-orbit-polarized heavy-hole systems in GaAs.