Non-universal Casimir effect in saturated superfluid 4He films at Tλ

27th International Conference on Low Temperature Physics

Abraham, John B.S.^1 ; Williams, Gary A.^1 ; Penanen, Konstantin^2

Department of Physics and Astronomy, University of California, Los Angeles

CA

90095, United States^1

Jet Propulsion Laboratory, California Institute of Technology, Pasadena

CA

91109, United States^2

关键词: Casimir effects;    Critical fluctuations;    Kosterlitz-Thouless;    Measurements of;    Onset temperature;    Second sound;    Superfluid density;    Superfluid transition temperature;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/568/1/012025/pdf
DOI  :  10.1088/1742-6596/568/1/012025

来源: IOP

【 摘 要 】

Measurements of Casimir effects in4He films in the vicinity of the bulk superfluid transition temperature Tλhave been carried out, where changes in the film thickness and the superfluid density are both monitored as a function of temperature. The Kosterlitz-Thouless superfluid onset temperature in the film is found to occur just as the Casimir dip in the film thickness from critical fluctuations becomes evident. Additionally, a new film-thickening effect is observed precisely at Tλwhen the temperature is swept extremely slowly. We propose that this is a non-universal Casimir effect arising from the viscous suppression of second sound modes in the film.