Room temperature multiferroicity in Bi rich Fe deficient Gd doped Bi1.2Gd0.1Fe0.8O3

A clean signature of room temperature multiferroicity in Bi1.2Gd0.1Fe0.8O3 ceramics is observed. Samples were prepared by slow step sintering technique at 850 °C. Impurity peaks normally present in original BiFeO3 are completely suppressed with the increase of Bi concentration. Apart from this, structural transformation took place from R3C to Pn21a space group and a clear orthorhombic grain growth habit is seen by SEM microstructure. Suppression of impurity phases favors the reduction of mobile oxygen vacancies and hence reduces leakage current for which ferroelectric properties of Bi1.2Gd0.1Fe0.8O3 are enhanced. We argue that the addition of Gd is likely to suppress the spiral spin modulation and at the same time increase the canting angle which favors the enhanced ferromagnetism. Excess Bi is expected to act as point defects and occupy interstitial positions which in turn surrounded by oxygen vacancies and is likely to promote defect driven ferromagnetism with enhanced spin and electric polarization. This finding encourages further revaluation of long-discounted BiFeO3 for multiferroics research.

Research highlights▶ Impurity peaks present in BiFeO3 are suppressed with the increase of Bi concentration. ▶ Structural transformation from R3C to Pn21a by substitution of excess Bi and Gd. ▶ Addition of Gd may suppress the spiral spin modulation with enhanced ferromagnetism. ▶ Suppression of oxygen vacancy & Fe+2 enhanced ferroelectricity by decreasing Fe ions.