Regensburg 2002 – wissenschaftliches Programm
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PV: Plenarvorträge
PV III
PV III: Plenarvortrag
Dienstag, 12. März 2002, 08:30–09:15, H1
Dirty Fermions and Fermi-Bose superfluids (3He and 3He –4He mixtures) in aerogel. — •Jeevak Parpia — Department of Physics and LASSP, Cornell University, Ithaca, NY 14853. USA
The first part of the presentation will provide a short overview of experimental progress toward the understanding of dirty superfluid 3He. Aerogel, an ultra dilute silica glass introduces correlated disorder to the purest material known, the p-wave paired superfluid, 3He. The silica strands are small in comparison to the zero temperature coherence length of 3He and so do not act as diffusely scattering surfaces which would completely suppress pairing. Instead, the system exhibits characteristics of a dirty superfluid, with a pairing amplitude that is reduced from its bulk value, and a significantly altered phase diagram.
We also report the first observation of coexisting and interacting superfluid Bose and Fermi components in 3He – 4He mixtures in aerogel. The mixture separates into a 4He-rich phase that coats the silica strands, and a pure 3He phase (at mk temperatures) that fills the interstices of the aerogel. The 4He component is a superfluid at temperatures lower than 300 mK. Below 2 mK, this inhomogeneous system exhibits simultaneous 3He and 4He superfluidity and the sound modes of the interpenetrating Fermi and Bose components of the superfluid are strongly coupled. It is likely that these acoustic signatures will prove useful in the observation of simultaneous superfluidity in homogenous mixtures of bosonic and fermionic atomic gases.
This research was funded by the National Science Foundation under DMR-9970817, and DMR-0071630