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Condensed Matter Seminars
| Condensed Matter
Thursday, October 27, 2005
Physics Building, Room 204
Note special time.
Note special room.
[Host: Jongsoo Yoon]
Penn State University
"Observation of Superflow in Solid He-4"
We have observed superflow in both bulk solid He-4 and
solid He-4 confined in porous media by torsional oscillator technique.
Below 0.25K non-classical rotational inertia appears as an abrupt drop in the
resonant period of the torsional oscillator.
The temperature dependence of the supersolid fraction is different from
those found in liquid helium and weakly interacting alkali gases.
The non-classical rotational inertia fraction is independent of the oscillation
speed below an extremely small critical value of 10 um/s, above which
strongly attenuated. The pressure dependence of the supersolid fraction in the
low temperature limit reveals an intriguing maxium around 55 bars, whereafter
the supersolid fraction monotonically decreases at least up to 136 bars and can
be linearly extrapolated to zero at 170 bars.
 E. Kim and M. H. W. Chan, Nature 427, 225 (2004); Science 305, 1941 (2004);
J. Low Temp. Phys. 138, 859 (2005).
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