Magnetic proximity effect in $\mathbf{YBa_2Cu_3O_7/La_{2/3}Ca_{1/3}MnO_3}$ and $\mathbf{YBa_2Cu_3O_7/LaMnO_{3+\delta}}$ superlattices

Abstract

Using neutron reflectometry and resonant x-ray techniques we studied the magnetic proximity effect (MPE) in superlattices composed of superconducting YBa$_2$Cu$_3$O$_7$ (YBCO) and ferromagnetic-metallic (FM-M) La$_{0.67}$Ca$_{0.33}$MnO$_{3}$ (LCMO) or ferromagnetic-insulating (FM-I) LaMnO$_{3+\delta}$ (LMO). We find that the MPE strongly depends on the electronic state of the manganite layers, being pronounced for the FM-M LCMO and almost absent for FM-I LMO. We also detail the change of the magnetic depth profile due to the MPE and provide evidence for its intrinsic nature.