QFS2016 Book of Abstracts

Abstracts

P1.6 Superfluid transitions of 4 He films under new dimensional and topological conditions of nanopores N. Wada(1), T. Matsushita(1), M. Hieda(2) 1)Department of Physics, Nagoya University, Nagoya 464-8602, Japan 2)Col. of Lib. Arts & Sci., Tokyo Medical and Dental Univ., 2-8-30 Kounodai, Ichikawa, 272-0827, Japan We have investigated various new superfluid(SF) transitions of the 4 He films formed in nanopores which have respective conditions of dimension and topology. The 4 He nanotubes formed in straight nanochannels show SF onset characteristic to 1D, due to thermal excitations of the 2 π -phase windings. In 3D nanopore, even thin film shows a typical 3D SF transition, where the thermal wavelength is large compared to the period of 3D pore connection. For a thick film in the 3D pore, we observed a successive phase change from normal to the 2D degenerate state followed by the 3D SF transition, in a marginal 2-to-3 dimension where the wavelength is obviously shorter than the 3D period. P1.7 Highly mobile metastable state of He solid layer on graphite: A glass formation by mechanical perturbation? Tomoki Minoguchi Institute of physics, University of Tokyo Solid layers of helium on graphite surface is known to undergo a highly mobile state (HMS) once the solid layer is enforced to slip on the substrate. The HMS collapses to the original inert state with the life time extending over 10 4 sec. In this paper, we suggest that the HMS is a structural glass by showing the similarities between the present system and BEDT-TTF. The latter was recently uncovered to be an electronic glass if the cooling rate is rapid enough across the freezing temperature (Wigner crystal formation temperature). We then suggest that a novel behavior on the metastability of glass should be seen for He-4 case as the condensation fraction grows in the liquid overlayer.

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