title: Superfluidity of dense 4He in vycor.
abstract: We calculate properties of a model of 4He in Vycor using the path integral Monte Carlo method. We find that 4He forms a distinct layered structure with a highly localized first layer, a disordered second layer with some atoms delocalized and able to give rise to the observed superfluid response, and higher layers of nearly perfect crystals. The addition of a single 3He atom was enough to bring down the total superfluidity by blocking the exchange in the second layer. Our results are consistent with the persistent liquid-layer model to explain the observations. Such a model may be relevant to the experiments on bulk solid 4He, if there is a fine network of grain boundaries in those systems.
authors.affiliation: Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA.
authors.forename: Saad A
authors.initials: SA
authors.lastname: Khairallah
authors.forename: D M
authors.initials: DM
authors.lastname: Ceperley