A simple system with two temperatures

TL;DR

This paper investigates a simple coupled spin system in a nonequilibrium steady state, revealing aging-like features and effective temperatures through response-correlation analysis.

Contribution

It introduces a minimal model demonstrating aging phenomena and effective temperatures in a nonequilibrium stationary regime.

Findings

Response vs. correlation plot shows aging features.

Identification of regimes with effective temperatures.

System exhibits nonequilibrium steady states similar to complex systems.

Abstract

We study the stationary nonequilibrium regime which settles in when two single-spin paramagnets each in contact with its own thermal bath are coupled. The response vs. correlation plot exhibits some features of aging systems, in particular the existence, in some regimes, of effective temperatures.