Magnetic pinning effect in YBa2Cu3O7−d/Nd0.35Sr0.65MnO3 bilayer

The coexistence of superconducting and magnetic ordering has attracted much attention for fundamental physics as well as applications, particularly in the hybrid systems of superconductor (SC)/ ferromagnet (FM). The magnetic exchange field of ferromagnetic coupling tends to break the symmetry ordering of superconductor;¹ whereas the cooper pairs penetrate into magnetic matter and also cause the proximity effect at the interface.² Among many, the enhancement of critical current density of high-T_c superconductors via magnetic pining is one of the important subjects in electronics. RBa₂Cu₃O_7-d (R = Y or rare earth element)-type superconductors are favorite candidates for applications because of their well-controlled pinning properties in magnetic field. The strengthening of pinning potential can be achieved via the addition of impurity phases by chemical mixing,³ columnar defects generated by heavy ion irradiation,⁴ and point defects generated by oxygen deficiency or chemical substitution.⁵ In this study, we report the effects of magnetic proximity on flux pining in high-Tc superconductor YBa₂Cu₃O_7-d (YBCO) by capping a C-type antiferromagnetic insulator Nd_0.35Sr_0.65MnO₃ (NSMO) on top of it.