QFS2016 Book of Abstracts

Abstracts

P1.29 Fluidity of domain walls in dilute 3 He– 4 He mixture monolayer films ≈ Possible 1D Fermi fluid and 2D Dirac fermions in helium film on graphite ≈ Morishita Masashi, Umemoto Masatoshi University of Tsukuba, Faculty of pure and applied sciences, Tsukuba, 305-8571, Japan To interpret the anomalous behaviors of measured heat capacity of dilute 3 He– 4 He mixture monolayer films, fluidity of domain walls and possible behaviors as 1D Fermi fluid and 2D Dirac fermions of mobile 3 He atoms in the domain walls have been proposed. In particular, observed anomalous T2-behavior of heat capacity can be attributed to the linear dispersion of the Dirac fermions. Existence of critical velocity of superfluidity of 4 He film due to the Landau criterion has also been proposed. To obtain more precise and definite information about the behavior of 3 He atoms, heat capacity measurements with smaller amount of 3 He atoms are in progress, and these results will also be presented. P1.30 Low temperature heat capacity of 4 He films on graphite Morishita Masashi University of Tsukuba, Faculty of pure and applied sciences, Tsukuba, 305-8571, Japan Helium-4 films adsorbed on graphite surfaces provide an ideal 2D boson system. At some areal densities, possible supersolidity has been reported. However, their properties have not been clearly understood yet. Heat capacities of 4 He films have been measured at rather low temperatures between 1 and 80 mK and at areal densities between 2 and 24 nm − 2 . Between 19 and 24 nm − 2 , small but definite bumps have been observed below 20 mK, whose origin has not been understood yet. On the other hand, the measured heat capacity above 30 mK hardly change between 13 and 24 nm − 2 , which suggests that the second atomic layer does not solidify at these areal densities, at least not into a commensurate solid.

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