Anomalous suppression of superfluidity for 4He in Gelsil glass

Abstract

We have studied the superfluid behavior of liquid 4He confined in three samples of Gelsil glass, whose pore size distribution was examined by measuring N2 pressure isotherm. It was found that the superfluid transition temperature under the saturation vapor pressure is 1.37 K for one of the samples whose pore size ranges up to around 6 nm, while it is 0.83 K for another one in which the distribution of pore size is small above 4 nm. Both of the samples have a bottleneck structure of the same size. These results demonstrate that the suppression of superfluidity is related to the pore size distribution rather than the size of the neck. © Published under licence by IOP Publishing Ltd.