Theoretical descriptions of the flow resistivity of very thin He-4 films near the Kosterlitz-Thouless transition

摘要

Massflow in superfluid He-4 films of only a few atomic layers thickness experiences flow resistance due to the dissipative motion of free vortices. Below the transition temperature these free vortices are generated by the flow through the breaking up of bound pairs, above the transition additional dissociation of pairs occurs spontaneously by thermal activation. In this paper a survey is presented of the present theoretical descriptions of the flow resistivity of very thin He-4 films. The assignation of the various film parameters, as they appear in the theory, to a film of given thickness at a given temperature is briefly discussed. In the subsequent paper the theories are applied to series of flow measurements on films on various substrates. (C) 2002 Elsevier Science B.V. All rights reserved. [References: 70]