Effect of competition between superconductivity and ferromagnetism in GdBa2Cu3O7-x/La0.7Sr0.3MnO3 bilayers

We studied the effect of substrate-induced strain state on the superconducting transition in GdBa2Cu3O7-x(GdBCO)/La0.7Sr0.3MnO3 (LSMO) bilayers deposited on a LaAlO3 (LAO) substrate. The stain state of LSMO is controlled by increasing the thickness from 20 nm to 80 nm. Analyses on the extended X-ray absorption fine structure (EXAFS) measurements reveal difference in the direction of MnO6 octahedral distortion depending on the LSMO thickness, which leads to a difference in anisotropy of magnetization of LSMO layer. The superconducting transitions of our system are strongly correlated with the magnetic anisotropy accompanied by the MnO6 octahedron distortion in a specific direction. This result suggests the possibility of improving the superconducting transition in the GdBCO/LSMO bilayer system by controlling the degree of competition between superconductivity and ferromagnetism via adjusting strain state in the LSMO layer.