RT Journal Article T1 Spin diffusion versus proximity effect at ferromagnet/superconductor La_(0.7)Ca_(0.3)MnO_(3)/YBa_(2)Cu_(3)O_(7-δ) interfaces A1 Peña, V. A1 Visani, C. A1 Garcia Barriocanal, Javier A1 Arias Serna, Diego A1 Sefrioui, Zouhair A1 León Yebra, Carlos A1 Santamaría Sánchez-Barriga, Jacobo A1 Almasán, Carmen A. AB We report on the interplay between magnetism and superconductivity in La_(0.7)Ca_(0.3)MnO_(3)/YBa_(2)Cu_(3)O_(7) structures. We have grown heterostructures (bilayers and trilayers) with a constant thickness of the ferromagnetic layer of 40 unit cells (15 nm) and changing the thickness of the superconductor between 1 (1.2 nm) and 40 unit cells (48 nm). The critical temperature of the bilayers decreases when the thickness of the superconductor is reduced below 10 unit cells, thus providing an estimate of the length scale of superconductivity suppression by spin-polarized quasiparticles in YBa_(2)Cu_(3)O_(7-δ) (YBCO) of 10 nm, much larger than the coherence length. For thickness of the YBCO layer smaller than 4 unit cells; a second mechanism of superconductivity depression comes into play, probably related to the ferromagnetic/superconducting proximity effect. The relative importance in depressing the critical temperature of intrinsic mechanisms (quasiparticle diffusion and proximity effect) and extrinsic ones (intralayer disorder, interface roughness, or reduced dimensionality of ultrathin layers) is discussed. PB American Physical Society SN 1098-0121 YR 2006 FD 2006-03-27 LK https://hdl.handle.net/20.500.14352/51417 UL https://hdl.handle.net/20.500.14352/51417 LA eng NO 1) Z. Radovic, L. Dobrosavljevic-Grujic, A. I. Buzdin, J. R. 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