Observation of non-classical rotational inertia in solid He-4 confined in porous gold

Abstract

Recent torsional oscillator measurements on solid He-4 confined in Vycor glass at 62 bars show supersolid response, an abrupt drop in. rotational moment of inertia, at 175 mK(1). We have investigated the pore-size dependence of the supersolid behavior by confining solid He-4 in a different porous host, porous gold, of a considerably larger pore diameter. When solid He-4 in porous gold is cooled below 0.2 K a sharp drop in. the resonant period is found. The supersolid response exhibits a strong dependence on the amplitude of oscillation.