Substrate-tuned boson localization in superfluid 4He films -: art. no. 235301

We have studied the influence of the substrate on superfluidity in thin He-4 films. The inert coverage, the amount of nonsuperfluid He-4 localized by the substrate, is found to scale with the well depth of the He-4-substrate interaction potential for six different substrates. Although the inert coverages for these substrates differ by more than a factor of 4, the phase boundary in the temperature-coverage plane is found to have a universal shape.