Normal-Superfluid Phase Separation in Spin-Half Bosons at Finite Temperature

TL;DR

This paper investigates phase separation in spin-half bosons at finite temperature, revealing a normal-superfluid coexistence, spinodal decomposition, and a gas-liquid-like transition without a critical point, observable in density profiles.

Contribution

It introduces the phenomenon of normal-superfluid phase separation in spin-half bosons with specific interactions at finite temperature, highlighting unique thermodynamic behaviors.

Findings

Normal-superfluid phase coexistence at finite temperature.

Spinodal decomposition causes phase separation.

Pressure-volume diagram shows a gas-liquid-like plateau.

Abstract

For pseudospin-half bosons with inter-spin attraction and intra-spin repulsion, normal phase and Bose condensed phase can coexist at finite temperature. The homogeneous system is unstable against the spinodal decomposition within a medium density interval, and consequently, a normal-superfluid phase separation takes place. The isothermal equation-of-state shows a characteristic plateau in the P-V (pressure-volume) diagram, which is reminiscent of a classical gas-liquid transition, although, unlike the latter, the coexistence lines never terminate at a critical point as temperature increases. In a harmonic trap, the phase separation can be revealed by the density profile of the atomic cloud, which exhibits a sudden jump across the phase boundary.