Oscillatory superconducting transition temperature in YBa2Cu4O8/La2/3Ca1/3MnO3/YBa2Cu4O8 heterostructures

Abstract: YBa2Cu4O8/La2/3Ca1/3MnO3/YBa2Cu4O8 (Y-124/LCMO/Y-124) heterostructures were prepared by facing-target sputtering technique. The oscillatory behavior of superconducting transition temperature (TC) with the thickness of LCMO (dL) has been observed. The strongest nonmonotonic information in TC–dL curves appears clearly when dL is larger than the critical thickness . The metal-insulator transition temperature (TMI) can only be detected at dL>. For LCMO/Y-124/LCMO trilayer films, the TMI has also shown an oscillation with decreasing spacer layer thickness. These kinds of symmetric dependence on the spacer layer in LCMO/Y-124 systems suggest strongly the interplay of ferromagnetic and superconducting couplings. [Copyright &y& Elsevier]