Effect of 3He on submonolayer superfluidity.

Abstract

We have studied the superfluid response of 3He-4He mixture films adsorbed onto porous gold for a wide range of 3He and 4He coverages, focusing on submonolayer superfluidity. At T = 0, 3He appears to float on top of 4He and can be viewed as a second substrate that induces its own inert layer. Depending on the 4He content, the zero-temperature superfluid mass and the superfluid onset temperature either saturate or vanish with the addition of 3He. The T = 0 superfluid-insulator phase boundary, which can be described by a simple function, is found in the 3He-4He coverage plane.