Transition temperature for ⁴He liquid adsorbed in disordered media

351-354For pure 4He liquid the superfluid fraction starts having a finite value at and below the -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