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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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