Magnetic-Field-Induced Hybridization of Electron Subbands in a Coupled Double Quantum Well

TL;DR

This study uses magnetocapacitance to explore how magnetic fields induce hybridization of electron subbands in a double quantum well, revealing complex quantum oscillations and energy gaps at very low temperatures.

Contribution

It demonstrates magnetic-field-induced hybridization of electron subbands in a coupled double quantum well, observed through quantum oscillations and energy gaps at low temperatures.

Findings

Observation of two sets of quantum oscillations from different subbands

Detection of common energy gaps at integer fillings

Evidence of magnetic-field-induced hybridization of electron subbands

Abstract

We employ a magnetocapacitance technique to study the spectrum of the soft two-subband (or double-layer) electron system in a parabolic quantum well with a narrow tunnel barrier in the centre. In this system unbalanced by gate depletion, at temperatures $T\agt 30$ mK we observe two sets of quantum oscillations: one originates from the upper electron subband in the closer-to-the-gate part of the well and the other indicates the existence of common gaps in the spectrum at integer fillings. For the lowest filling factors $\nu=1$ and $\nu=2$, both the common gap presence down to the point of one- to two-subband transition and their non-trivial magnetic field dependences point to magnetic-field-induced hybridization of electron subbands.