Phase Diagram of ³He in Aerogel

The figure shows the measured superfluid transition of ³He in aerogel. The transition temperature is lower than in pure ³He (dashed line), and depends on the density and properties of the aerogel. The measurements are from Porto and Parpia (triangles) [1], Sprague et al (boxes) [2], and Matsumoto et al (circles) [3]. There is evidence of both A phase [2] and B phase [4,5]. Recently, both A and B phases have been observed in the same experiment [6].

The aerogel is very porous and occupies only 2% of the volume. Theoretically aerogel is considered as an impurity, which in the simplest approximation is distributed homogeneously, and thus analogous to impurities in superconducting metals.

1. J.V. Porto and J.M. Parpia, Phys. Rev. Lett. 74, 4667 (1995).
2. D.T. Sprague, T.M. Haard, J.B. Kycia, M.R. Rand, Y. Lee, P.J. Hamot, and W.P. Halperin, Phys. Rev. Lett. 75, 661 (1995).
3. K. Matsumoto, J.V. Porto, L. Pollack, E.N. Smith, T.L. Ho, and J.M. Parpia, Phys. Rev. Lett. 79, 253 (1997).
4. D.T. Sprague, T.M. Haard, J.B. Kycia, M.R. Rand, Y. Lee, P.J. Hamot, and W.P. Halperin, Phys. Rev. Lett. 77, 4568 (1996).
5. H. Alles, J.J. Kaplinsky, P.S. Wootton, J.D. Reppy, J.H. Naish, and J.R. Hook, Phys. Rev. Lett. 83, 1367 (1999).
6. B.I. Barker, Y. Lee, L. Polukhina, D.D. Osheroff, L.W. Hrubesh, and J.F. Poco, Phys. Rev. Lett. 85, 2148 (2000).

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