Analysis of the proximity effect and the interface transparency with perpendicular current in Ni/Nb system

Abstract

We quantitatively study the interface resistance in Ni/Nb multilayers fabricated by sputtering system. For a fixed Ni layer thickness in Ni/Nb/Ni trilayers, the superconducting temperature T(c) decreases with decreasing Nb thickness. By analyzing the data with the proximity effect, the critical thickness below which superconductivity vanished was deduced. From current perpendicular to plane (CPP) measurement interpreted with a one-band series-resistor model, we obtained the CPP resistivities of Nb and Ni and the unit area resistances of 4.2 +/- 0.2 and 1.5 +/- 0.4 f Omega m(2) for superconducting and normal Ni/ Nb interfaces. The transparency parameter is directly calculated in terms of interface resistance. (C) 2009 American Institute of Physics. [DOI: 10.1063/1.3073657]