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- Title
Critical Behavior of the Liquid Gas Transition of He Confined in a Silica Aerogel.
- Authors
Aubry, G.; Bonnet, F.; Melich, M.; Guyon, L.; Despetis, F.; Wolf, P.
- Abstract
We have studied He confined in a 95 % porosity silica aerogel in the vicinity of the bulk liquid gas critical point. Both thermodynamic measurements and light scattering experiments were performed to probe the effect of a quenched disorder on the liquid gas transition, in relation with the Random Field Ising Model (RFIM). We find that the hysteresis between condensation and evaporation present at lower temperatures disappears at a temperature T between 25 and 30 mK below the critical point. Slow relaxations are observed for temperatures slightly below T, indicating that some energy barriers, but not all, can be overcome. Above T, no density step is observed along the (reversible) isotherms, showing that the critical behavior of the equilibrium phase transition in presence of disorder, if it exists, is shifted to smaller temperatures, where it cannot be observed due to the impossibility to reach equilibrium. Above T, light scattering exhibits a weak maximum close to the pressure where the isotherm slope is maximal. This behavior can be accounted for by a simple model incorporating the compression of He close to the silica strands.
- Subjects
LIQUID helium; SILICA; AEROGELS; POROSITY; THERMODYNAMICS; RANDOM fields; LOW temperature physics; PHASE transitions
- Publication
Journal of Low Temperature Physics, 2013, Vol 171, Issue 5/6, p670
- ISSN
0022-2291
- Publication type
Article
- DOI
10.1007/s10909-012-0740-2