Barrier enhancement behavior in an Au/BiFeO3/YBa2Cu3O7-δ/SrTiO3 heterostructure with the magnetic field effect

Leakage current density of BiFeO3/YBa2Cu3O7-δ multiferroic/superconductor bilayers on SrTiO3 substrate were systemically studied in the temperature range 30-160 K under magnetic fields up to 11 T. With increasing magnetic field, the leakage current density J-E characteristics show a slight increase behavior near the superconducting transition temperature Tc of YBa2Cu3O7-δ and could be fitted by the model of Schottky emission. Especially, The Schottky barrier height at the BiFeO3/YBa2Cu3O7-δ interface decreases with increasing magnetic field at Tc. In addition, the magnetic field dependence of the maximal deviation of Schottky barrier height is consistent with the calculated values of the superconducting gap versus magnetic field. The manipulation of anomalous leakage current density by the superconductivity is demonstrated to be probably related to the opening of the superconducting gap, which is useful for designing multi-functional devices in spintronics.