Condensation of helium in aerogels and athermal dynamics of the Random Field Ising Model

TL;DR

This study demonstrates that helium condensation in aerogels exhibits a disorder-driven critical point linked to out-of-equilibrium dynamics, highlighting the importance of non-equilibrium effects in disordered phase transitions.

Contribution

It provides experimental evidence connecting helium condensation in aerogels to the athermal critical behavior of the Random Field Ising Model, emphasizing non-equilibrium effects.

Findings

Condensation isotherms become discontinuous below a critical temperature.

Discontinuous behavior is due to out-of-equilibrium dynamics, not equilibrium phase transition.

Results support the relevance of the RFIM in disordered system phase transitions.

Abstract

High resolution measurements reveal that condensation isotherms of $^4$He in a silica aerogel become discontinuous below a critical temperature. We show that this behaviour does not correspond to an equilibrium phase transition modified by the disorder induced by the aerogel structure, but to the disorder-driven critical point predicted for the athermal out-of-equilibrium dynamics of the Random Field Ising Model. Our results evidence the key role of non-equilibrium effects in the phase transitions of disordered systems.