The structural and superconducting properties in the YBa2Cu3O7−δ/BiFeO3 heterostructures

Using pulsed laser deposition, the (0 0 1)-oriented YBa2Cu3O7−δ (YBCO) films were epitaxially grown on BiFeO3 (BFO) films on SrTiO3 substrates. The YBCO/BFO heterostructure retained the ferroelectricity of BFO layer and the superconductivity of the YBCO layer. A ferroelectric hysteresis loop was observed in the BFO layer and the remnant polarization was approximately 4.6 μC/cm2. The fabrication of YBCO layer resulted in a c-axis decrease of BFO layer, which affected its ferroelectric properties. Especially, as increasing the thickness of BFO film, the superconducting transition width of YBCO film increased. And the c-axis of YBCO film tended towards stability at 11.7 Å which ensured that all the samples were superconductive. The YBCO/BFO heterostructure could be used to fabricate YBCO Josephson junctions and the YBCO and BFO multilayers.