Anticrossings of spin-split Landau levels in an InAs two-dimensional electron gas with spin-orbit coupling

Abstract

We report tilted-field transport measurements in the quantum Hall regime in an $\mathrm{In}\mathrm{As}∕{\mathrm{In}}_{0.75}{\mathrm{Ga}}_{0.25}\mathrm{As}∕{\mathrm{In}}_{0.75}{\mathrm{Al}}_{0.25}\mathrm{As}$ quantum well. We observe anticrossings of spin-split Landau levels, which suggest a mixing of spin states at Landau level coincidence. We propose that the level repulsion is due to the presence of spin-orbit and of band-nonparabolicity terms which are relevant in narrow-gap systems. Furthermore, electron-electron interaction is significant in our structure, as demonstrated by the large values of the interaction-induced enhancement of the electronic $g$ factor.