Confinement of two-dimensional excitons in a non-homogeneous magnetic field

TL;DR

This paper derives an effective Hamiltonian for 2D excitons in non-homogeneous magnetic fields, showing how field gradients can trap excitons and alter their properties, with specific calculations for GaAs systems.

Contribution

It introduces a new theoretical framework for exciton confinement in non-uniform magnetic fields and demonstrates trapping effects in GaAs quantum wells.

Findings

Excitons can be trapped in low magnetic field regions due to field gradients.

The trapping energy depends strongly on the magnetic field profile.

Non-homogeneous magnetic fields modify exciton mass and energy.

Abstract

The effective Hamiltonian describing the motion of an exciton in an external non-homogeneous magnetic field is derived. The magnetic field plays the role of an effective potential for the exciton motion, results into an increment of the exciton mass and modifies the exciton kinetic energy operator. In contrast to the homogeneous field case, the exciton in a non-homogeneous magnetic field can also be trapped in the low field region and the field gradient increases the exciton confinement. The trapping energy and wave function of the exciton in a GaAs two-dimensional electron gas for specific circular magnetic field configurations are calculated. The results show than excitons can be trapped by non-homogeneous magnetic fields, and that the trapping energy is strongly correlated with the shape and strength of the non-homogeneous magnetic field profile.