Structural and Electrical Properties of Epitaxial La2/3Ca1/3MnO3/La1/3Ca2/3MnO3/YBa2Cu3O7−δ Trilayers

Trilayers made of perovskite-type ferromagnetic (F), antiferromagnetic (AF) and superconducting (S) films were fabricated and their microstructural properties studied. Epitaxially strained La2/3Ca1/3MnO3/La1/3Ca2/3MnO3/YBa2Cu3O7−δ (F/AF/S) trilayers were grown in situ by dc-sputtering technique onto (001)-oriented SrTiO3 (STO) substrates. Whereas the thickness of the bottom (F) and top (S) layer was fixed to 74 nm and 100 nm, respectively, that of the intermediate AF layer was varied between ∼4 nm and ∼9 nm. The crystalline quality of the samples was checked by X-Ray diffraction (XRD) analysis. The θ–2θ scans and reciprocal space maps at (002) and (013) Bragg reflections provided clear evidence for the heteroepitaxial growth of the trilayers as well as for the absence of secondary phases. Due to high epitaxiality of the trilayers, their magnetic response was already shown to develop an excellent magnetic anisotropy to clearly visualize the superconducting diamagnetism and ferromagnetic behavior at a same temperature. The superconducting diamagnetic response at 5 K has now been used to calculate the superconducting current density of the S layer as a function of an applied magnetic field. The results confirmed the uncoupling role of the AF layer. The presence of well defined AF barriers (La1/3Ca2/3MnO3) in the trilayers was also evidenced by recording the I–V characteristic in cross configuration, which showed an anisotropic behavior as well. The results achieved suggest that such oxide heterostructures could play an important role in the search for novel devices based on magnetic junctions.