Phase transition of Two-timescale Two-temperature Spin-lattice Gas Model

TL;DR

This paper investigates phase transitions in a nonequilibrium spin-lattice gas model with two degrees of freedom operating on different time scales, revealing conditions for negative latent heat and analyzing phase diagram differences.

Contribution

It derives a general thermodynamic condition for negative latent heat and applies mean-field analysis to uncover phase diagram features in a two-timescale, two-temperature model.

Findings

Negative latent heat appears regardless of time scale order.

Phase diagram exhibits qualitative differences due to nonequilibrium conditions.

A thermodynamic criterion for anomalous phase transitions is established.

Abstract

We study phase transition of a nonequilibrium statistical-mechanical model, in which two degrees of freedom with different time scales separated from each other touch to their own heat bath. A general condition for finding anomalous negative latent heat recently discovered is derived a from thermodynamic argument. As a specific example, phase diagram of a spin-lattice gas model is studied based on a mean-field analysis with replica method. While configurational variables are spin and particle in this model, it is found that the negative latent heat appears in a parameter region of the model, irrespective of the order of their time scale. Qualitative differences in the phase diagram are also discussed.