Pseudo diamagnetism of four component exciton condensates

TL;DR

This paper investigates the spin structure of four-component exciton condensates in quantum wells, revealing pseudo-diamagnetism and first-order transitions driven by magnetic field and spin interactions.

Contribution

It introduces a detailed analysis of the spin-dependent behavior and magnetic response of four-component exciton condensates, highlighting the pseudo-diamagnetism phenomenon.

Findings

Chemical potential increases with magnetic field indicating pseudo-diamagnetism.

Transitions to polarized condensates can be first-order.

Energy mixing of exciton states causes the observed effects.

Abstract

We analyze the spin structure of the ground state of four-component exciton condensates in coupled quantum wells as a function of spin-dependent interactions and applied magnetic field. The four components correspond to the degenerate exciton states characterized by $\pm2$ and $\pm1$ spin projections to the axis of the structure. We show that in a wide range of parameters, the chemical potential of the system increases as a function of magnetic field, which manifests a pseudo-diamagnetism of the system. The transitions to polarized two- and one-component condensates can be of the first-order in this case. The predicted effects are caused by energy conserving mixing of $\pm2$ and $\pm1$ excitons.