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Superfluidity of Pure 3He and Mixtures of 3He and 4He in Aerogel

Authors
  • Golov, A.1
  • Porto, J. V.1
  • Matsumoto, K.1
  • Pollack, L.1
  • Smith, E. N.1
  • Biggar, R. D.1
  • Ho, T. L.1
  • Parpia, J. M.1
  • 1 Cornell University, Laboratory of Atomic & Solid State Physics, Ithaca, NY, 14853, USA , Ithaca
Type
Published Article
Journal
Journal of Low Temperature Physics
Publisher
Kluwer Academic Publishers-Plenum Publishers
Publication Date
Jan 01, 1998
Volume
110
Issue
1-2
Pages
515–523
Identifiers
DOI: 10.1023/A:1022502715336
Source
Springer Nature
Keywords
License
Yellow

Abstract

We describe new torsional oscillator experiments on3He confined in 98.2% open aerogel. In one, we monitored the superfluid fraction of pure3He at T << Tcwhile we gradually changed the sample pressure. The resulting change in density alters ξ0of the superfluid3He relative to the distribution of the length scales (correlations) of silica in the aerogel. We observed a T = 0 normal-to-super fluid transition at a pressure of about 6.5 bar, in marked contrast to the bulk where liquid3He is superfluid at all pressures. In the second experiment, we measured the temperature dependence of the3He ρsat a pressure of 21.6 bar with different amounts of4He present in the cell. Adding 2-3%4He slightly increases both Tcand ρs. We found that for4He concentrations between 2% and 34%, the3He Tcincreases by a very small amount. However, ρs, which for pure3He in aerogel at 0.5Tcis no more than 11%, falls by another factor of 7. This behavior (constant Tc, reduced ρs) is similar to that observed in granular superconducting films where the long-range order is controlled by phase coherence between adjacent grains.

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