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Keywords:

  • superconductor/ferromagnet proximity effect;
  • cuprate superconductors;
  • manganites.

Abstract

We fabricated high-quality YBa2Cu3O7-δ/La2/3Ca1/3 MnO3 bilayers with 10 monolayers (∼ 12 nm) thin superconducting YBa2Cu3O7-δ (YBCO)layers on top of ferromagnetic La2/3Ca1/3MnO3 (LCMO) layers with a thickness varied between 5 and 35 monolayers (∼ 2–13 nm). We measured the transport properties of the YBCO layers and the magnetic properties of the LCMO layers as a function of the LCMO layer thickness. We observed a smooth linear increase of the Curie temperature TC of the LCMO layer in the investigated thickness range, but a sudden strong decrease of the superconducting critical temperature Tc of the YBCO layer at a critical LCMO thickness of ∼ 12 nm. Since no dramatic change of the structural quality of the YBCO layers is observed we conclude that the increasing magnetization strength in the LCMO layer is responsible for the Tc suppression in the YBCO layer via proximity effect.