Thermodynamic inequalities in superfluid

TL;DR

This paper derives new thermodynamic inequalities that replace the Landau criterion for superfluid stability at finite temperatures, considering an extended set of thermodynamic variables including superfluid velocity and momentum density.

Contribution

It introduces a generalized framework for superfluid stability analysis using thermodynamic inequalities in an extended variable space, advancing beyond traditional criteria.

Findings

Derived thermodynamic inequalities for superfluid stability.

Replaced Landau criterion at finite temperatures.

Extended stability analysis to include superfluid velocity and momentum density.

Abstract

We investigate general thermodynamic stability conditions for the superfluid. This analysis is performed in an extended space of thermodynamic variables containing (along with the usual thermodynamic coordinates such as pressure and temperature) superfluid velocity and momentum density. The stability conditions lead to thermodynamic inequalities which replace the Landau superfluidity criterion at finite temperatures.