Critical current in Nb-Cu-Nb junctions with nonideal interfaces

Abstract

We report on experimental studies of superconductor (Nb) -normal metal (Cu) -superconductor (Nb) junctions with dirty interfaces between the different materials. By using a set of simultaneously prepared samples, we investigated the thickness dependence as well as the temperature dependence of the critical currents in the junctions. Good agreement between the decay of the measured critical currents and theoretical calculations was obtained without any fitting parameters.

Non-hysteretic superconducting quantum interference proximity transistor with enhanced responsivity

“…20 For the ideal junction, I C / R À1 N in which R N ¼ ql=A is the normal-state resistance of the SNS junction, q ¼ 1=ð F e 2 DÞ is the island resistivity, A is the island cross section, F is the density of states at the Fermi level in N, and D is the diffusion coefficient of the normal metal. [21][22][23] The hysteresis is suppressed at low temperatures by increasing the Josephson inductance of the junction. 23,24 We achieved this by shrinking the cross section A of the weak-link which leads to an increased normal-state resistance and Josephson inductance.…”

Josephson effect in superconductor/ferromagnet-normal/superconductor structures

“…[1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] The analysis of existing experimental data 16,17 have shown that the value of exchange energy H in ferromagnetic materials used in [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] scales is in between 850 and 2300 K. This leads to effective decay length F1 Ϸ 1.2-4.6 nm and period of oscillations F2 Ϸ 0.3-2 nm of thickness dependence of a S/F/S junction critical current I C . These values turned out to be much smaller compared to the decay length N Ϸ 10-100 nm, in similar S/normal metal ͑N͒/S structures.…”

Theory of the Josephson effect in unconventional superconducting junctions with diffusive barriers

“…SFS junctions have been realized experimentally by several groups. [19][20][21][22][23][24][25][26][27][28][29] In d-wave superconductor junctions, one of the most remarkable phenomena is the formation of midgap Andreev resonant states ͑MARSs͒ at interfaces. 30 The MARSs stem from a sign change of pair potentials of d-wave superconductors.…”