Exciton dispersion measurement and control

Magnetic field was experimentally shown to be an effective tool for a measurement and control of quasi-2D exciton effective mass and dispersion relation.

When an in-plane magnetic field is applied, the exciton dispersion surface shifts. This results to the transition from the momentum-space direct exciton ground state to the momentum-space indirect exciton ground state and, consequently, to a strong enhancement of the indirect exciton lifetime, thus further lowering the indirect exciton effective temperature.

Application of in-plane magnetic fields also allows measurement of the exciton dispersion.

Perpendicular magnetic fields result in enhancement of the effective mass of QW excitons. This effect originates from the coupling between the exciton internal structure and center of mass motion induced by magnetic field.

Effect of perpendicular magnetic field on exciton condensation

The effect of perpendicular magnetic field on the quantum degeneracy of the 2D exciton gas and the exciton condensation has a complicated character. There are "good" effects, which increase the quantum degeneracy and improve the critical conditions for the exciton condensation, and there are "bad" effects, which reduce the quantum degeneracy and suppress the exciton condensation.