Correlation Between Ferromagnetism and Superconductivity at Interfaces of La2/3Ca1/3MnO3/YBa2Cu3O7−δ /La2/3Ca1/3MnO3 Trilayers Grown by dc Sputtering
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In this work, we study the magnetoelectrical properties of La2/3Ca1/3MnO3/YBa2Cu3O7−δ /La2/3Ca1/3MnO3 heterostructures grown by means of high oxygen-pressure dc sputtering onto (001)-oriented SrTiO3 substrates. The test heterostructures are composed of ferromagnetic layers of constant thicknesses (∼280 unit cells, ∼110 nm) and superconducting interlayers with thicknesses ranging between 5 (∼6 nm) and 15 unit cells (∼17 nm). Transport measurements show a strong suppression of the superconducting properties when the thickness of the YBa2Cu3O7−δ interlayer is reduced to a value below 10 unit cells. Magnetic measurements show superconducting transition in junctions with YBa2Cu3O7−δ interlayers with thicknesses larger than ∼15 unit cells. The observed difference in the values of the superconductivity onset when determined by electrical and magnetic measurements might be related with the presence of a spontaneous vortex phase in the temperature range around the superconducting transition.
KeywordsVortex lattices Flux pinning Flux creep Manganites High-Tc films
The authors wish to thank the thin films group at the “Universidad del Valle” in Cali-Colombia for the assistance with the preparation of the samples. One of the authors (O.M.) acknowledges the financial support of the German Service of Academic Interchange (DAAD) through the program “Wiedereinladung.”