Critical velocity of antiferromagnetic spin-1 Bose-Einstein condensates at finite temperature

TL;DR

This paper investigates the critical velocity at which a moving antiferromagnetic spin-1 Bose-Einstein condensate becomes unstable, focusing on spin excitations and temperature effects using Landau's criterion.

Contribution

It provides a detailed analysis of the instability mechanism in spinor BECs, highlighting the role of spin-carrying quasiparticles and temperature dependence of the critical velocity.

Findings

Spin-carrying quasiparticles trigger instability first.

Critical velocity decreases with increasing temperature.

Finite-temperature effects modify the instability threshold.

Abstract

We study the instability of a moving spinor Bose-Einstein condensate when the speed of flow reaches the critical velocity. This we identify on the basis of Landau's criterion, i.e. the velocity above which some elementary excitation energy becomes negative. We show that the first-to-become unstable excitations are spin-carrying quasiparticles. We also discuss the temperature dependence of the critical velocity in a more advanced mean-field approximation.