Compensation of Dipolar-Exciton Spin Splitting in Magnetic Field

TL;DR

This study investigates how exchange interactions in dense dipolar exciton gases can completely compensate for spin splitting in a magnetic field, revealing new insights into exciton behavior in quantum wells.

Contribution

It demonstrates the complete compensation of spin splitting in dipolar excitons due to exchange interactions, supported by experimental magnetoluminescence data.

Findings

Complete spin-splitting compensation below 2 Tesla.

Large blue shift up to 3 meV at low magnetic fields.

Qualitative agreement with theoretical models of exchange interaction.

Abstract

Magnetoluminescence of spatially indirect dipolar excitons collected in 25 nm GaAs/AlGaAs single quantum well within a lateral potential trap has been studied in perpendicular magnetic field in Faraday geometry. The paramagnetic spin splitting of the luminescence line of the heavy-hole excitons in the trap centre is completely compensated at magnetic fields below critical value, around 2 Tesla. The effect of spin-splitting compensation is caused by the exchange interaction in dense exciton Bose gas which is in qualitative agreement with the existing theoretical concepts. In the range of low magnetic fields, less than 1.5 Tesla, an unusually large blue shift, upto 3 meV, is observed, which is related to in-plane electric field component present in nonhomogeneous electrostatic field of the trap.