Reduced ferroelectric coercivity in multiferroic Bi0.825Nd0.175FeO3 thin film

Abstract

${\mathrm{Bi}}_{0.825}{\mathrm{Nd}}_{0.175}\mathrm{Fe}{\mathrm{O}}_3$ (BNFO) thin film is grown on $\mathrm{Pt}∕\mathrm{Ti}{\mathrm{O}}_2∕\mathrm{Si}{\mathrm{O}}_2∕\mathrm{Si}$ substrate by pulsed laser deposition, and its multiferroic properties are compared with those of $\mathrm{Bi}\mathrm{Fe}{\mathrm{O}}_3$ (BFO) thin film. With limited ${\mathrm{Fe}}^{2+}$ ions and its twinborn oxygen vacancies, both samples show low dielectric losses of $<0.026$ at $100\mathrm{Hz}$ and high maximum ferroelectric polarizations of $\sim 34\mu \mathrm{C}∕{\mathrm{cm}}^2$ . The ferroelectric coercive field of BNFO is reduced by $\sim 40\%$ , reaching a low value of $235\mathrm{kV}∕\mathrm{cm}$ , compared to that of BFO due to the increased ratio of 180° and curved ferroelectric domains to total ferroelectric domains and better nucleation of the ferroelectric domains at the BNFO∕Pt interface. The Raman scattering spectra confirm that the ferroelectric polarizations of both samples originate in the stereochemical activity of the Bi lone electron pair. Weak ferromagnetism is observed in both samples as a result of the limited amount of ${\mathrm{Fe}}^{2+}$ ions and $\gamma \text{‐}{\mathrm{Fe}}_2{\mathrm{O}}_3$ impurity.