Enhancement of the spin-gap in fully occupied two-dimensional Landau levels

TL;DR

This study investigates how the spin-gap in fully occupied Landau levels of a 2D electron gas in CdTe quantum wells is enhanced by many-body effects and spin polarization, using magneto-luminescence and transport measurements.

Contribution

It provides new insights into the spin-splitting behavior of Landau levels, highlighting the role of many-body interactions and spin polarization in a 2DEG system.

Findings

Spin splitting includes Zeeman and many-body contributions.

Both contributions cause a rigid shift of Landau level ladders.

Spin polarization influences the magnitude of the spin-gap.

Abstract

Polarization-resolved magneto-luminescence, together with simultaneous magneto-transport measurements, have been performed on a two-dimensional electron gas (2DEG) confined in CdTe quantum well in order to determine the spin-splitting of fully occupied electronic Landau levels, as a function of the magnetic field (arbitrary Landau level filling factors) and temperature. The spin splitting, extracted from the energy separation of the \sigma+ and \sigma- transitions, is composed of the ordinary Zeeman term and a many-body contribution which is shown to be driven by the spin-polarization of the 2DEG. It is argued that both these contributions result in a simple, rigid shift of Landau level ladders with opposite spins.