New superconductor/ferromagnet heterostructure formed by YBa2Cu3O7âˆ' x and CaRuO3.

Almost all proposed configurations and practical achievements based on superconductor/ferromagnet (S/F) heterostrucutres focus on s-wave superconductors. However, several attempts targeted also high temperature superconductors, most of them using manganite ferromagnets LaXMnO₃ (X: Ca or Sr) and Y₁Ba₂Cu₃O_{7âˆ' x} (YBCO). Here we propose a new ferromagnetic material that can be used with YBCO for the fabrication of S/F hybrid structures. We show that a ferromagnetic order can be induced in a thin layer (∼130 nm thickness) of CaRuO₃ grown by pulsed laser deposition on epitaxial YBCO film. Detailed magnetic and structural investigations show that the observations of the weak ferromagnetism are consistent with the magnetic order induced by in-plane tensile strain of about 1.7% and the easy-magnetization axis forms an angle of ∼180Âş with the layer plane. The value of the Curie temperature T _Curie estimated using the Curieâ€"Weiss law was 340 K. An unusual temperature dependence of the magnetic moment around the superconducting transition was observed in both field-cooled and zero-field-cooled configurations which is attributed to the paramagnetic Meissner effect. [ABSTRACT FROM AUTHOR]