Visani, CristinaSefrioui Khamali, ZouhairTornos Castillo, JavierVillegas Hernández, Javier EulogioLeón Yebra, CarlosBriatico, J.Bibes, ManuelBarthelemy, AgnesSantamaría Sánchez-Barriga, Jacobo2024-01-312024-01-312012-05-13Visani, C., Sefrioui, Z., Tornos, J. et al. Equal-spin Andreev reflection and long-range coherent transport in high-temperature superconductor/half-metallic ferromagnet junctions. Nature Phys 8, 539–543 (2012). https://doi.org/10.1038/nphys231810.1038/nphys2318https://hdl.handle.net/20.500.14352/97161Está depositada la versión postprint del artículoConventional superconductivity is incompatible with ferromagnetism, because the magnetic exchange field tends to spin-polarize electrons and breaks apart the opposite-spin singlet Cooper pairs(1). Yet, the possibility of a long-range penetration of superconducting correlations into strong ferromagnets has been evinced by experiments that found Josephson coupling between superconducting electrodes separated afar by a ferromagnetic spacer(2-7). This is considered a proof of the emergence at the superconductor/ferromagnetic (S/F) interfaces of equal-spin triplet pairing, which is immune to the exchange field and can therefore propagate over long distances into the F (ref. 8). This effect bears much fundamental interest and potential for spintronic applications(9). However, a spectroscopic signature of the underlying microscopic mechanisms has remained elusive. Here we do show this type of evidence, notably in a S/F system for which the possible appearance of equal-spin triplet pairing is controversial(10-12): heterostructures that combine a half-metallic F (La0.7Ca0.3MnO3) with a d-wave S (YBa2Cu3O7). We found quasiparticle and electron interference effects in the conductance across the S/F interfaces that directly demonstrate the long-range propagation across La0.7Ca0.3MnO3 of superconducting correlations, and imply the occurrence of unconventional equal-spin Andreev reflection. This allows for an understanding of the unusual proximity behaviour observed in this type of heterostructures(12,13).engAttribution 4.0 Internationalhttp://creativecommons.org/licenses/by/4.0/journal article1745-2481https://doi.org/10.1038/nphys2318open access538.9Física del estado sólido2211 Física del Estado Sólido