Polarization bistability and resultant spin rings in semiconductor microcavities

TL;DR

This paper demonstrates how polarization-dependent interactions in semiconductor microcavities lead to bistability and the formation of spin rings, with a phenomenological model accurately describing these phenomena.

Contribution

It introduces a model incorporating spin-dependent interactions and incoherent reservoir effects to explain polarization bistability and spin ring formation in microcavities.

Findings

Polarization bistability causes spin ring patterns.

Spin-dependent interactions control internal polarization.

A phenomenological model matches experimental observations.

Abstract

The transmission of a pump laser resonant with the lower polariton branch of a semiconductor microcavity is shown to be highly dependent on the degree of circular polarization of the pump. Spin dependent anisotropy of polariton-polariton interactions allows the internal polarization to be controlled by varying the pump power. The formation of spatial patterns, spin rings with high degree of circular polarization, arising as a result of polarization bistability, is observed. A phenomenological model based on spin dependent Gross-Pitaevskii equations provides a good description of the experimental results. Inclusion of interactions with the incoherent exciton reservoir, which provides spin-independent blueshifts of the polariton modes, is found to be essential.