Enhanced Magnetic and Ferroelectric Properties and Current-Voltage Hysteresis by Addition of La and Ti to BiFeO₃ on 0.7%Nb−SrTiO₃

By adding La and Ti, we improve the magnetic and ferroelectric properties of Bi_0.8La_0.2Fe_0.92Ti_0.08O₃ and Bi_0.8La_0.2FeO₃ films on 0.7%Nb−SrTiO₃. In Bi_0.8La_0.2Fe_0.92Ti_0.08O₃ and Bi_0.8La_0.2FeO₃, the saturation magnetization and the coercivity are several times higher than those in BiFeO₃. The La and Ti additions reduce the leakage current, and increase the remnant electric polarization. A resistance switching is observed in Bi_0.8La_0.2Fe_0.92Ti_0.08O₃/0.7%Nb−SrTiO₃ and Bi_0.8La_0.2FeO₃/0.7%Nb−SrTiO₃ interfaces. Also, it is observed that Bi_0.8La_0.2Fe_0.92Ti_0.08O₃/0.7%Nb−SrTiO₃ has a wider current−voltage hysteresis and a larger resistance difference than Bi_0.8La_0.2FeO₃/0.7%Nb−SrTiO₃. In the interface of Bi_0.8La_0.2Fe_0.92Ti_0.08O₃/0.7%Nb−SrTiO₃, the ratio of high to low resistance is 10³ and 10⁵ times, at 300 K and 10 K, respectively. The voltage pulses can switch the resistance to vary in the 2 states. The transport mechanisms show that a trap−controlled space-charge-limited current induces current-voltage hysteresis and resistance switching. The current of Bi_0.8La_0.2Fe_0.92Ti_0.08O₃/0.7%Nb−SrTiO₃ decays with the Curie–Von Schweidler law.