Hybridization of electron subbands in a double quantum well at quantizing magnetic field

TL;DR

This study investigates the hybridization of electron subbands in a double quantum well under a magnetic field using magnetocapacitance and spectroscopy, revealing how hybridization affects the energy gaps at specific filling factors.

Contribution

It introduces a simple model to describe hybrid gaps in a double quantum well system, advancing understanding of subband interactions in magnetic fields.

Findings

Hybrid gaps at filling factors ν=1 and ν=2 are observed.

Hybridization causes modifications in the bilayer spectrum.

Both trivial and hybridization-induced gaps are identified.

Abstract

We employ magnetocapacitance and far-infrared spectroscopy techniques to study the spectrum of the double-layer electron system in a parabolic quantum well with a narrow tunnel barrier in the centre. For gate-bias-controlled asymmetric electron density distributions in this soft two-subband system we observe both individual subband gaps and double layer gaps at integer filling factor $\nu$. The bilayer gaps are shown to be either trivial common for two subbands or caused by hybridization of electron subbands in magnetic field. We describe the observed hybrid gaps at $\nu=1$ and $\nu=2$ within a simple model for the modified bilayer spectrum.