Spin gap in the 2D electron system of GaAs/AlGaAs single heterojunctions in weak magnetic fields

TL;DR

This paper investigates how spin gaps in a 2D electron system in GaAs/AlGaAs heterojunctions are affected by weak magnetic fields, revealing that spin excitations involve single flips rather than skyrmions.

Contribution

It provides experimental measurements of interaction-enhanced spin gaps using magnetocapacitance, challenging the skyrmion-based interpretation of excitations at certain filling factors.

Findings

Spin gaps increase with parallel magnetic field.

Charged excitations involve single spin flips.

Skyrmions are not the lowest-energy excitations at nu=1 and nu=3.

Abstract

We study the interaction-enhanced spin gaps in the two-dimensional electron gas confined in GaAs/AlGaAs single heterojunctions subjected to weak magnetic fields. The values are obtained from the chemical potential jumps measured by magnetocapacitance. The gap increase with parallel magnetic field indicates that the lowest-lying charged excitations are accompanied with a single spin flip at the odd-integer filling factor nu=1 and nu=3, in disagreement with the concept of skyrmions.