Phase Slips and Parity Jumps in Quantum Oscillations of Inverted InAs/GaSb Quantum Wells

TL;DR

This study investigates the quantum Hall effect in inverted InAs/GaSb quantum wells, revealing spin-splitting, phase slips near π, and complex Landau level filling due to hybridization and charge transfer between electron-like and hole-like states.

Contribution

It provides new insights into Landau level structure and phase behavior in hybridized quantum wells, highlighting effects of spin-orbit interaction and charge transfer on quantum oscillations.

Findings

Spin-orbit interaction causes significant spin-splitting of hole-like states.

Discrete phase slips near π are observed in quantum oscillations.

Quantum Hall states exhibit periodic even and odd filling factors due to hybridization.

Abstract

We present magnetotransport measurements of a strongly hybridized inverted InAs/GaSb double quantum well. We find that the spin-orbit interaction leads to an appreciable spin-splitting of hole-like states, which form distinct Landau levels in a perpendicular magnetic field. The resulting quantum Hall state is governed by a periodic even and odd total filling arising due to the simultaneous occupation of electron-like and hole-like Landau levels of differing degeneracy. Furthermore, oscillatory charge transfer between all involved subbands leads to discrete phase slips in the usual sequential filling of Landau levels, and coincidentally the phase slips are close to $\pi$. These results shed new insights on the Landau level structure in composite systems and have consequences for interpreting intercepts obtained from index plots, which are routinely employed to investigate the presence of Berry's phase.