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

Geoffroy Aubry (1) , Fabien Bonnet (1) , Mathieu Melich (1) , Laurent Guyon (1) , Panayotis Spathis (1) , Florence Despetis (2) , Pierre-Etienne Wolf (1)

1 NEEL - HELFA - Hélium : du fondamental aux applications
2 L2C - Laboratoire Charles Coulomb

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.

Mots clés: out-of-equilibrium phase transition; liquid-vapor transition; disorder; Random Field Ising Model; avalanches; hysteresis; helium; silica aerogel

Domaines: Systèmes désordonnés et réseaux de neurones [cond-mat.dis-nn]

Geoffroy Aubry, Fabien Bonnet, Mathieu Melich, Laurent Guyon, Panayotis Spathis, et al.. Condensation of helium in aerogels and athermal dynamics of the Random Field Ising Model. Physical Review Letters, 2014, 113 (8), pp.085301. ⟨10.1103/PhysRevLett.113.085301⟩. ⟨hal-00858215v3⟩