Critical temperature and interface transparency of N/S/N triple layers: theory and experiment

Proximity effect and interface transparency in Nb/Cu multilayers

“…One way to determine these quantities is to analyze the T c ͑d S ͒ data in N/S/N hybrids. 18,19 However, it has been shown that the experimental T c ͑d S ͒ dependence can be reproduced by an infinite number of pairs of ͑T , N ͒ when, as in the case of the samples used in this study, d S and d N ͑the thickness of the normal metal layer͒ are larger than S and N , respectively. This means that only when it is possible to obtain N by independent measurements, the curve T͑ N ͒ unambiguously gives the value of the interface transparency.…”

“…For N we choose Cu while Nb was taken as the superconducting metal. To obtain information on the interface transparency of this system, the experimental data have been interpreted using a theoretical model in which a matrix method has been developed to exactly solve the Usadel equations which describe the critical state of S/N multilayers, 18 using the boundary conditions developed in Ref. 12.…”

“…3, T c ͑N b ͒ dependence for Cu/ ͓Nb/ Cu͔ N b multilayers, have been both interpreted using the same model developed in Ref. 18. This model, which describes the properties of S/N structures, contains five independent parameters.…”

“…The quantity ␣ is order of unity and N,max is the largest value of the normal metal coherence length for which experimental data are theoretically reproduced using an ideal transparent interface: T =1. 18 In Fig. 2 the experimental points of the T c ͑d S ͒ dependence are shown by closed symbols.…”

Upper critical fields and interface transparency in superconductor/ferromagnet bilayers

“…[7][8][9] The parameter which has been added to the proximity effect theory to describe the role of the boundary among different layers is the interface transparency, which has been extensively studied, theoretically and experimentally, for S / F as well as for S / N structures ͑here N stands for normal metal͒, in particular, in relation to its influence on the behavior of T c as a function of d S ͑the thickness of the superconducting layer͒ and d F ͑or d N , the thickness of the normal layer͒. [7][8][9][10][11][12][13][14] Also relevant is the expected effect of the interfaces on the temperature dependence of the critical magnetic fields in layered structures. In fact, when the field is applied in the direction parallel to layers, the Cooper pairs move crossing the boundaries and, consequently, experiencing the influence of the interface resistance.…”