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Proximity-induced Josephson effect and its application to heavy-fermion superconductor UBe/sub 13/

Thesis/Dissertation ·
OSTI ID:7079343

A new effect between a superconductor with superconducting transition temperature T/sub CS/ and a normal metal N(T/sub cn/) (or another superconductor with T/sub cn/ < T/sub cs/) was experimentally observed and theoretically explained. That is, when S and N are brought together to form a weak link, the Josephson effect can occur in this SN system even in the temperature range T/sub cn/ < T < T/sub cs/, when the N side is in the normal state. This Josephson effect is believed to happen between the S and a region of proximity-induced super-conductivity in N near the contact with S. This is called the proximity-induced Josephson effect. The temperature dependence of the Josephson critical current I/sub c/(T) of the SN point-contact junctions have been studied experimentally. The experiments were performed on Ta/Mo, Ta/UBe/sub 13/, and Nb/Ta point contact, etc. The theoretical model is based on the linearized Gor'kov equation (or linearized Ginzburg-Landau equation) combined with de Gennes boundary conditions. Along with the recent discovery of the superconductivity in heavy-fermion materials CeCu/sub 2/Si/sub 2/, UBe/sub 13/, and UPt/sub 3/, the old question of p-wave pairing superconductivity is raised again (in case of the existence of strong spin-orbit scattering, it should be called odd-parity superconductivity, since in that case the wave function of Cooper pairs cannot be separated into spin part and orbit part).

Research Organization:
Iowa State Univ. of Science and Technology, Ames (USA)
OSTI ID:
7079343
Country of Publication:
United States
Language:
English