Transition temperature for ⁴He liquid adsorbed in disordered media

Abstract

For pure ⁴He liquid the superfluid fraction starts having a finite value at and below the <img src='/image/spc_char/lamda.gif' border=0>-transition temperature 2.176K, whereas for ⁴He in a disordered media the superfluid fraction starts having a finite value at 2.168K, a temperature that is lower compared to the temperature at which superfluidity appears in pure ⁴He. Relations for transition temperatures for both cases that are in agreement with experimental values have been obtained. Adsorption, which normally leads to a decrease in the degrees of freedom, consequently results in a release of heat, which destroys superfluidity. Hence for the liquid ⁴He flowing into a disordered medium, the transition temperature is expected to be lower.