Giant Low Temperature Heat Capacity of GaAs Quantum Wells near Landau Level Filling $\nu$=1

TL;DR

This study measures the heat capacity of GaAs quantum wells at very low temperatures in the quantum Hall regime, revealing a giant enhancement near Landau level filling factor 1 due to Skyrmions and potential phase transitions.

Contribution

It provides the first detailed low-temperature heat capacity data showing Skyrmion effects and nuclear-electron coupling in GaAs quantum wells near $ u$=1.

Findings

Heat capacity is up to 10^5 times larger near $ u$=1.

Data suggest strong coupling between nuclear spins and the lattice.

Evidence of a possible phase transition at very low temperatures.

Abstract

We report low temperature ($T$) heat capacity ($C$) data on a multiple-quantum-well GaAs/AlGaAs sample in the quantum Hall regime. Relative to its low field magnitude, $C$ exhibits up to 10^5-fold enhancement near $\nu$=1 where Skyrmions arethe ground state of the confined two-dimensional electrons. We attribute the large $C$ to a Skyrmion-induced, strong coupling of the nuclear spin system to the lattice. The data are consistent with the Schottky nuclear heat capacity of Ga and As atoms in the quantum wells, except at very low $T$ where $C$ vs $T$ exhibits a remarkably sharp peak suggestive of a phase transition in the electronic system.