Spin polarized semimagnetic exciton-polariton condensate in magnetic field

TL;DR

This paper demonstrates a semimagnetic exciton-polariton condensate with high spin polarization under moderate magnetic fields, revealing new spin-related phenomena and enabling advanced studies of spin-polarized condensates.

Contribution

It introduces a semimagnetic polariton system with enhanced Zeeman splitting, showing high spin polarization and power-dependent spin behavior, which was not observed in nonmagnetic systems.

Findings

Achieved over 95% circular polarization in condensate emission at 3 T

Observed increase in spin polarization with excitation power

Demonstrated magnetic field-induced polariton condensation

Abstract

Owing to their integer spin, exciton-polaritons in microcavities can be used for observation of non-equilibrium Bose-Einstein condensation in solid state. However, spin-related phenomena of such condensates are difficult to explore due to the relatively small Zeeman effect of standard semiconductor microcavity systems and the strong tendency to sustain an equal population of two spin components, which precludes the observation of condensates with a well defined spin projection along the axis of the system. The enhancement of the Zeeman splitting can be achieved by introducing magnetic ions to the quantum wells, and consequently forming semimagnetic polaritons. In this system, increasing magnetic field can induce polariton condensation at constant excitation power. Here we evidence the spin polarization of a semimagnetic polaritons condensate exhibiting a circularly polarized emission over 95% even in a moderate magnetic field of about 3 T. Furthermore, we show that unlike nonmagnetic polaritons, an increase on excitation power results in an increase of the semimagnetic polaritons condensate spin polarization. These properties open new possibilities for testing theoretically predicted phenomena of spin polarized condensate.