Tunneling between Dilute GaAs Hole Layers

TL;DR

This study investigates interlayer tunneling in dilute GaAs hole layers, revealing unexpected spectral features and evidence of a bilayer quantum Hall ferromagnet at specific conditions, challenging existing models.

Contribution

It demonstrates that a Fermi liquid model can describe the tunneling spectrum shape and temperature dependence, despite anomalously large peak amplitudes and novel magnetic field effects.

Findings

Tunneling spectrum matches Fermi liquid model shape and temperature dependence.

Observation of a zero-bias peak recurrence at high magnetic fields.

Detection of a narrow tunneling peak at total filling factor ν_T=1 indicating a quantum Hall ferromagnet.

Abstract

We report interlayer tunneling measurements between very dilute two-dimensional GaAs hole layers. Surprisingly, the shape and temperature-dependence of the tunneling spectrum can be explained with a Fermi liquid-based tunneling model, but the peak amplitude is much larger than expected from the available hole band parameters. Data as a function of parallel magnetic field reveal additional anomalous features, including a recurrence of a zero-bias tunneling peak at very large fields. In a perpendicular magnetic field, we observe a robust and narrow tunneling peak at total filling factor $\nu_T=1$, signaling the formation of a bilayer quantum Hall ferromagnet.