Third sound measurements of superfluid 4He films on multiwall carbon nanotubes below 1 K

27th International Conference on Low Temperature Physics

Menachekanian, Emin^1 ; Abraham, John B.S.^1 ; Chen, Bob^1 ; Iaia, Vito^1 ; Li, Andrew^1 ; Williams, Gary A.^1

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

CA

90095, United States^1

关键词: Annular resonators;    Atomic layer;    Kosterlitz-Thouless transitions;    Layer completions;    Linear variation;    Mechanical oscillations;    Superfluid films;    Temperature sweeps;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/568/1/012026/pdf
DOI  :  10.1088/1742-6596/568/1/012026

来源: IOP

【 摘 要 】

Third sound is studied for superfluid films of 4He adsorbed on multiwall carbon nanotubes packed into an annular resonator. The third sound is generated with mechanical oscillation of the cell, and detected with carbon bolometers. A filling curve at temperatures near 250 mK shows oscillations in the third sound velocity, with maxima at the completion of the 4th and 5th atomic layers. Sharp changes in the Q factor of the third sound are found at partial layer fillings. Temperature sweeps at a number of fill points show strong broadening effects on the Kosterlitz-Thouless (KT) transition, and rapidly increasing dissipation, in qualitative agreement with the predictions of Machta and Guyer. At the 4th layer completion there is a sudden reduction of the transition temperature TKT, and then a recovery back to linear variation with temperature, although the slope is considerably smaller than the KT prediction.