Regensburg 2000 – wissenschaftliches Programm
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TT: Tiefe Temperaturen
TT 17: Postersitzung II: Pinning und Vortexdynamik (1-8), Supraleitung: Theorie (9-13), Korrelierte Elektronen (14-48), Niederdimensionale Systeme (49-68), Quantenflüssigkeiten (69-75)
TT 17.70: Poster
Mittwoch, 29. März 2000, 14:30–18:00, A
Thermal Coupling between Compacted Ag Powder and Liquid 3He at Very Low Temperatures — •I. Usherov-Marshak, R. König, and G. Eska — Physikalisches Institut, Universität Bayreuth, 95440 Bayreuth
The deviation of the temperature dependence of the thermal boundary resistance RK between liquid 3He and compacted powders at T ≤ 10 mK from the acoustic mismatch theory (RK ∝ T−3 ) is usually attributed to two different origins: a magnetic and an acoustic channel for the heat transfer. However, the origin of both coupling mechanisms is not yet understood. In particular, there is a qualitative and quantitative difference in the magnetic field dependence of RK between compacted Pt- and Ag-powder and liquid 3He, respectively [1,2].
We discuss preliminary results of our measurements of the Kapitza resistance between normal and superfluid 3He and compacted Ag powder. In the temperature range 0.8 ≤ T ≤ 1.4 mK and at B = 0, we find RK ∝ T−1. At T = 2.5 mK and at fields 0 ≤ B ≤ 500 mT we observe the magnetic field dependence RK(B) as reported by Osheroff and Richardson [1]: RK increases with magnetic field and saturates at B = 150 mT. Further measurements of RK on Ag and Pt samples, along with our studies of the magnetic properties of the metal powder compacts, should provide a better understanding of the coupling of these materials to liquid 3He.
[1] Osheroff and Richardson, PRL 54 1178 (1985)
[2] Perry et al., PRL 48 1831 (1982)