The transport properties in BiFeO 3 /YBCO heterostructures

BiFeO3 (BFO)/YBCO heterostructures are fabricated on (001)-oriented SrTiO3 substrates. The transport properties of BFO/YBCO heterostructures with Au and YBCO top electrode are investigated. The Au/BFO/YBCO heterostructures show obvious rectification effect. The current through Au/BFO/YBCO heterostructures at positive bias is mainly bulk-limited space-charge-limited current (SCLC) at temperatures from 15 K to 280 K. As the applied voltage on Au electrode is negative, Au/BFO/YBCO heterostructures satisfy the interface-limited Schottky emission at temperatures from 220 K to 300 K, instead of interface-limited Fowler-Nordheim tunneling at temperatures from 15 K to 80 K. The leakage current density is reduced by two orders of magnitude through substituting the Au electrode by YBCO electrode. The transport mechanism in YBCO/BFO/YBCO heterostructures also changes to SCLC. The different leakage mechanisms result from the reduced oxygen vacancies because the fabrication of YBCO layer increased oxygen concentration in BFO films. (C) 2015 Elsevier B.V. All rights reserved.