Student Thesis Seminar
"Proximity effect in granular superconductor-normal metal structures"
Itay Sternfeld
Dept. of Condensed Matter Physics, Tel Aviv University
We fabricated three-dimensional disordered Pb-Cu granular structures,
with various metal compositions. The typical grain size of both metals
is smaller than the superconductor and normal metal coherence lengths,
thus satisfying the Cooper limit. The critical temperature of the
samples was measured and compared with the critical temperature of
bilayers. We show how the proximity effect theories, developed for
bilayers, can be modified for random mixtures and we demonstrate that
our experimental data fit well the de Gennes weak coupling limit
theory in the Cooper limit. Our results indicate that, in granular
structures, the Cooper limit can be satisfied over a wide range of
concentrations.
Thesis Adviser: Prof. Alexander Palevsky, x8193
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