We have systematically studied the size- or frequency- dependent superfluid transition in 4He films adsorbed on porous glasses with pore diameters 's from 50 to 10000A, using two sets of torsional oscillators containing different pore size glasses with a common 4He inlet. It is clarified that the transition temperature Tc is determined by the vortex pair unbinding on length scales comparable to the characteristic lengths, the half of the pore circumference π d 2 or the vortex diffusion length rd.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Electrical and Electronic Engineering