Ferromagnetic/superconducting proximity effect in La0.7Ca0.3MnO3/YBa2Cu3O7−δ superlattices

Abstract

We study the interplay between magnetism and superconductivity in high-quality ${\mathrm{YBa}}_2{\mathrm{Cu}}_3{\mathrm{O}}_7\left(\mathrm{YBCO}\right)/{\mathrm{La}}_{0.7}{\mathrm{Ca}}_{0.3}{\mathrm{MnO}}_3\left(\mathrm{LCMO}\right)$ superlattices. We find evidence for the YBCO superconductivity depression in the presence of the LCMO layers. We show that due to its short coherence length, superconductivity survives in the YBCO down to a much smaller thickness in the presence of the magnetic layer than in low $T_c$ superconductors. We also find that for a fixed thickness of the superconducting layer, superconductivity is depressed over a thickness interval of the magnetic layer in the 100 nm range. This is a much longer length scale than that predicted by the theory of ferromagnetic/superconducting proximity effect.