Dresden 2006 – wissenschaftliches Programm

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TT: Tiefe Temperaturen

TT 7: Superconductivity & Solids At Low Temperature - Poster Session

TT 7.7: Poster

Montag, 27. März 2006, 14:00–17:45, P1

Influence of aluminium substitution on the heat transport in single crystalline MgB₂ — •A.V. Sologubenko^1,2, N.D. Zhigadlo², S. M. Kazakov², J. Karpinski², and H.R. Ott² — ¹II. Physikalisches Institut, University of Cologne, 50937 Cologne, Germany — ²Laboratorium für Festkörperphysik, ETH Hönggerberg, CH-8093 Zürich, Switzerland

We report data on the thermal conductivity κ(T,H) of single-crystalline superconducting Mg_1−yAl_yB₂ (y= 0.02, 0.07) in the normal and mixed states at temperatures between 0.5 and 50 K, and in external magnetic fields H up to 50 kOe. The results are analyzed in terms of a combined phononic (κ_ph) and quasiparticle (κ_e) heat transport and compared with our earlier results on pure and carbon-doped MgB₂. The substitution of Al for Mg leads to a considerable reduction of the field-induced κ_e, while κ_ph seems to be much less sensitive to impurities. The analysis of the κ_e (H) data leads to the conclusion that the introduction of aluminium results in comparable enhancement of the intraband scattering in both the σ- and the π-band. This is in contrast to the carbon substitution for boron, which enhances mostly the intraband scattering in the σ-band. The interband scattering is rather weak in both cases.