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TT: Tiefe Temperaturen

TT 23: Posters Superconductivity, Solids at Low Temperature

TT 23.5: Poster

Montag, 7. März 2005, 14:00–18:00, Poster TU D

Mn substitution in MgB₂ single crystals: influence on structural properties — •G. Schuck, N.D. Zhigadlo, S.M. Kazakov, K. Rogacki, and J. Karpinski — Solid State Physics Laboratory ETH-Hönggerberg, CH-8093 Zürich, Switzerland.

Superconducting single crystals of Mn-doped MgB₂ phase have been grown at a pressure of 30 kbar using cubic anvil technique. Critical temperature versus Mn content dependence of single crystals shows different behavior from that of polycrystalline samples [1], because even small substitution of 1.5% of Mn decreases T_c by about 15K. The lattice constant a remains almost unchanged while the c parameter slightly decreases with Mn content. Single crystal X-ray and EDX investigations show the existence of single phase crystals up to 2% Mn substitution. For crystals with higher Mn content we present single crystal determination in order to get information on what crystallographic position Mn is substituted in the MgB₂ crystal structure.

[1] S. Xu, Y. Moritomo, K. Kato and A. Nakamura, J. Phys. Soc. Japan, 70 (2001) 1889-1891