Fabrication and leakage current and ferroelectric characteristics of multiferroic Fe3O4/(Bi3.25Nd0.65Eu0.10)Ti3O12 composite thin films with Fe3O4 magnetic electrodes micropatterned by reactive ion etching

Abstract

Regardless of the deposition time (30–90 min), almost single-phase magnetite (Fe3O4) films with a cubic inverse-spinel structure were produced at a substrate temperature of 500 °C by metalorganic chemical vapor deposition (MOCVD). The Fe3O4/(Bi3.25Nd0.65Eu0.10)Ti3O12 (BNEuT) composite film deposited at 500 °C for 90 min by MOCVD exhibited excellent room-temperature magnetic properties, such as a saturation magnetization of 480 emu/cm3, a residual magnetization of 160 emu/cm3, and a coercivity of 297 Oe. Ferromagnetic Fe3O4 electrodes micropatterned using a combination of photolithography and reactive ion etching were fabricated after MOCVD, and their structural, leakage current, and ferroelectric characteristics were investigated. The room-temperature leakage current density–applied electric field and polarization–electric field (P–E) characteristics of the composite films were successfully measured using Fe3O4 electrodes. The room-temperature P–E hysteresis loop for a sample with the structure Fe3O4/BNEuT/Nb:TiO2/Ti had a relatively good shape, with a remanent polarization of 8 µC/cm2 and a coercive field of 193 kV/cm.