Dresden 2003 – scientific programme

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TT: Tiefe Temperaturen

TT 8: Supraleitung: Dünne Schichten, Josephsonkontakte, SQUIDs

TT 8.2: Talk

Tuesday, March 25, 2003, 10:00–10:15, HSZ304

Proximity Effects in CeCu₆/Nb Bilayers — •A. Otop^1,2, A. Otop^1,2, S. Süllow¹, M.B.S. Hesselberth², R.W.A. Hendrikx², C. Ciuhu³, A. Lodder³, J. Aarts², S. Süllow¹, M.B.S. Hesselberth², R.W.A. Hendrikx², C. Ciuhu³, A. Lodder³, and J. Aarts² — ¹Institut für Metallphysik und Nukleare Festkörperphysik, TU Braunschweig, Germany — ²Kamerlingh Onnes Laboratory, Leiden University, The Netherlands — ³Vrije Universiteit, Amsterdam, The Netherlands

We studied the proximity effect in CeCu₆/Nb bilayers in order to probe the response of the heavy-fermion metal CeCu₆ to induced superconductivity. High-quality CeCu₆ films were grown by DC-magnetron sputter deposition. The stoichiometry of the samples was checked by Rutherford Backscattering. Resistivity measurements on 75 nm and 188 nm thick CeCu₆ films reproduce the resistivity of bulk CeCu₆. Using the same preparation conditions as for single CeCu₆ films, bilayers of CeCu₆(75 nm)/Nb(d_Nb) were prepared, with the Nb thickness d_Nb varying between 10 nm and 50 nm. We determined the superconducting transition temperature T_c as a function of Nb film thickness and the parallel critical fields H_c2^|| as a function of temperature. We observe a strong suppression of T_c(d_Nb). Furthermore in the dependence of parallel critical field measurement H_c2^|| of the temperature no dimensional crossover (DCO) is observed, unlike the behaviour in superconductor / normal metal proximity systems. We discuss the measurements in the framework of the Takahashi-Tachiki theory for metallic multilayers and show that the heavy-fermion properties (low Fermi velocity and high density-of-states) are needed to explain the results.