Evidence for a disorder driven phase transition in the condensation of 4He in aerogels

Fabien Bonnet (1) , Thierry Lambert , Benjamin Cross , Laurent Guyon (1) , Florence Despetis (2) , Laurent Puech (1) , Pierre-Etienne Wolf (1)

1 NEEL - HELFA - Hélium : du fondamental aux applications
2 GES - Groupe d'étude des semiconducteurs

We report on thermodynamic and optical measurements of the condensation process of $^4$He in three silica aerogels of different microstructures. For the two base-catalysed aerogels, the temperature dependence of the shape of adsorption isotherms and of the morphology of the condensation process show evidence of a disorder driven transition, in agreement with recent theoretical predictions. This transition is not observed for a neutral-catalysed aerogel, which we interpret as due to a larger disorder in this case.

Mots clés: désordre; isothermes d'adsorption; transition liquide-gaz; aerogel; helium

Domaines: Matière Molle [cond-mat.soft]; Mécanique statistique [cond-mat.stat-mech]

Fabien Bonnet, Thierry Lambert, Benjamin Cross, Laurent Guyon, Florence Despetis, et al.. Evidence for a disorder driven phase transition in the condensation of 4He in aerogels. EPL - Europhysics Letters, 2008, 82 (5), pp.56003. ⟨10.1209/0295-5075/82/56003⟩. ⟨hal-00257998⟩