Thermodynamics of a Bose Einstein condensate with free magnetization

TL;DR

This paper investigates how free magnetization and dipole-dipole interactions influence the thermodynamics and phase transitions of a spin-3 chromium Bose-Einstein condensate, revealing critical temperature shifts and novel spin-dependent phases.

Contribution

It introduces a detailed analysis of the thermodynamics of a spin-3 BEC with free magnetization, highlighting the effects of dipole interactions and magnetic field on condensation and spin phases.

Findings

Critical temperature decreases at very low magnetic fields.

Depolarized gas condenses in a single spin component.

A spin thermometry method effective below degeneracy temperature.

Abstract

We study thermodynamic properties of a gas of spin 3 52Cr atoms across Bose Einstein condensation. Magnetization is free, due to dipole-dipole interactions (DDIs). We show that the critical temperature for condensation is lowered at extremely low magnetic fields, when the spin degree of freedom is thermally activated. The depolarized gas condenses in only one spin component, unless the magnetic field is set below a critical value, below which a non ferromagnetic phase is favored. Finally we present a spin thermometry efficient even below the degeneracy temperature.