Compressed Silica Aerogels for the Study of Superfluid [superscript 3]He

Conference · Fri Mar 02 04:00:00 EST 2007

OSTI ID:1008982

Pollanen, J; Choi, H; Davis, J P; Blinstein, S; Lippman, T M; Lurio, L B; Mulders, N; Halperin, W P ^[1]

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1. NIU

We have performed Small Angle X-ray Scattering (SAXS) on uniaxially strained aerogels and measured the strain-induced structural anisotropy. We use a model to connect our SAXS results to anisotropy of the {sup 3}He quasiparticle mean free path in aerogel. Measurements of the low temperature phase diagram of superfluid {sup 3}He in 98% aerogel indicate a stable B-phase and a metastable A-like phase. Vicente et al. proposed that the relative stability of these phases can be attributed to local anisotropic scattering of the 3He quasiparticles by the aerogel network. This network consists of silica strands with a diameter of {approx} 30 {angstrom} and average separation {zeta}{sub a} {approx} 300 {angstrom}. Vicente et al. also proposed using uniaxial strain of the aerogel to produce global anisotropy. We have performed SAXS on two uniaxially strained aerogels and found that strain introduces anisotropy on the {approx}100 {angstrom} length scale. We relate this to anisotropy of the quasiparticle mean free path, {lambda}.

• Research Organization: Advanced Photon Source (APS), Argonne National Laboratory (ANL), Argonne, IL (US)
• Sponsoring Organization: USDOE
• OSTI ID: 1008982
• Country of Publication: United States
• Language: ENGLISH

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ANISOTROPY
HELIUM 3
MEAN FREE PATH
PHASE DIAGRAMS
PHYSICS
SCATTERING
SILICA
STABILITY
STRAINS
SUPERFLUIDITY