Leakage mechanisms of double-perovskite Bi₂FeMnO₆ epitaxial thin films

Multiferroic Bi₂FeMnO₆ epitaxial thin films were deposited on conductive SrRuO₃/SrTiO₃ (0 0 1) substrate by pulse laser deposition. The Au/Bi₂FeMnO₆/SrRuO₃ capacitor structure was used to investigate the electrical property. Bi₂FeMnO₆ thin film has a good ferroelectric retention and the downward polarization state. For Bi₂FeMnO₆ film, different leakage mechanisms play a predominant role under different electric field regions. Ohmic conduction works under 80 kV cm⁻¹. From 80 to 1350 kV cm⁻¹, the leakage mechanism depends on the electric field polarity and Poole–Frenkel emission is the dominant mechanism at negative bias. Schottky emission dominates the leakage current above 1350 kV cm⁻¹. The extracted zero-field ionization energy for Poole–Frenkel emission is ∼0.4 eV. A schematic energy band alignment of Au/Bi₂FeMnO₆/SrRuO₃ capacitor was constructed to describe the contribution of Schottky emission. (paper)