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

Abstract

Bi[sub 0.825]Nd[sub 0.175]FeO₃ (BNFO) thin film is grown on Pt/TiO₂/SiO₂/Si substrate by pulsed laser deposition, and its multiferroic properties are compared with those of BiFeO₃(BFO) thin film. With limited Fe[sup 2+] ions and its twinborn oxygen vacancies, both samples show low dielectric losses of <0.026 at 100 Hz and high maximum ferroelectric polarizations of ~34 µC/cm². The ferroelectric coercive field of BNFO is reduced by ~40%, reaching a low value of 235 kV/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 Fe[sup 2+] ions and γ-Fe₂O₃ impurity.