Superconductor (YBa_2Cu_3O_(7-δ)) and ferromagnetic (La_(0.67)Ca_(0.33)MnO_3) heterojunctions: Role of epitaxy-scheme

摘要

Good quality bilayers of ferromagnetic/superconductor (F/S) and superconductor/ferromagnetic (S/F) heterostructures were prepared by pulsed laser deposition. Detailed magnetization studies on these structures were carried out using a SQUID magnetometer. Notwithstanding, the identical growth condition, the epitaxial sequence seems to greatly influence the magneto-transport properties of these structures. The superconducting property of the first structure(F/S) is retained, while in the latter (S/F) structure, it is seriously impaired. We suggest that the contrasting behaviour of the two, otherwise similar, structures originates from the predominance of either of the two competing phenomena at the interface, namely, Andreev reflections and quasiparticle tunneling.