Superconducting current in hybrid structures with an antiferromagnetic interlayer

Artikel i vetenskaplig tidskrift, 2010

It is shown experimentally that the superconducting current density in Nb/Au/Ca1 - x Sr (x) CuO2/YBa2Cu3O7 - delta hybrid superconducting heterostructures with a Ca1 - x Sr (x) CuO2 anti-ferromagnetic (AF) cuprate interlayer is anomalously high for interlayer thicknesses d (M) = 10-50 nm and the characteristic damping length for superconducting correlations is on the order of 10 nm. The experimental results are explained on the basis of theoretical analysis of a junction of two superconductors (S' and S) connected by a magnetic multilayer with the AF ordering of magnetization in the layers. It is shown that with such a magnetization ordering, anomalous proximity effect determined by the singlet component of the condensate wavefunction may take place. As a result, the critical currents in S'/I/AF/S and S'/I/N/S structures (I denotes an insulator, and N, the normal metal) may coincide in order of magnitude even when the thickness of the AF interlayer considerably exceeds the decay length of the condensate wavefunction in ferromagnetic layers.