Volume 82, Number 5, June 2008
Article Number 56003
Number of page(s) 6
Section Condensed Matter: Structural, Mechanical and Thermal Properties
Published online 23 May 2008
EPL, 82 (2008) 56003
DOI: 10.1209/0295-5075/82/56003

Evidence for a disorder-driven phase transition in the condensation of $\chem{^4He}$ in aerogels

F. Bonnet1, T. Lambert1, B. Cross1, L. Guyon1, F. Despetis2, L. Puech1 and P. E. Wolf1

1  Institut Néel, CNRS-UJF - BP 166, 38042 Grenoble-Cedex 9, France, EU
2  Groupe d'Etude des Semiconducteurs, CNRS-UMR 5650, Université Montpellier II - Case Courrier 074, 34095 Montpellier-Cedex 5, France, EU

received 19 February 2008; accepted in final form 14 May 2008; published June 2008
published online 23 May 2008

We report on thermodynamic and optical measurements of the condensation process of 4He 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.

64.60.-i - General studies of phase transitions.
64.70.F- - Liquid-vapour transitions. - Quantum fluids and solids: 4He: Films and restricted geometries.

© EPLA 2008