Münster 1997 – scientific programme
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TT: Tiefe Temperaturen
TT 19: Postersitzung III: Josephsonkontakte(1-25), SQUIDs, Sensoren, Detektoren(26-37), Supraleitung in Hochfrequenz und Elektronik(38-45), Präparation und Dotierung von HTSL(46-53), NMR und Ultraschall in HTSL(54-60), Thermodynamik, Magnetismus(61-68), Transporteigenschaften von HTSL(69-73), Spektroskopie, Ramanstreuung, param. Meissner-Effekt in HTSL(74-84), n-dotierte HTSL(85-91)
TT 19.73: Poster
Thursday, March 20, 1997, 15:30–19:00, Z1
High Resolution Thermal Conductivity Measurements of Bi2212 Crystals — •P. Esquinazi, A. Inyushkin, and A. Taldenkov — Abt. Supraleitung u. Magnetismus, Universität Leipzig, 04103 Leipzig
We have studied the thermal conductivity κ of Bi2212 High-Tc crystals at 7 K ≤ T ≤ 120K and fields 0 T ≤ Ba ≤ 8T in parallel and perpendicular orientations. The highest resolution achieved in our system is 0.1 % for a temperature drop across the sample of 20 mK at 100 K; the temperature stability is better than 1 mK at 100 K. The main results are: (a) we measure the maximum of κ at T ≃ 0.85 Tc and it is ∼ 5% larger than the value near Tc; (b) on cooling κ starts to increase and becomes field dependent far above the critical temperature Tc ≃ 89 K; (c) within our error no anomaly can be recognized in κ(T,Ba) around the melting transition; (d) the field dependent measurements show that κ−1 ∝ Ba for T > Tc and κ−1 ∝ Ba2/3 for T ≤ Tc. The implications of our results to the open questions: (a) main carriers: electrons or phonons?, (b) spin- and flux line lattice- phonons interactions, (c) fluctuations contributions to κ, will be discussed.