Large negative magnetoelectric coupling in Fe substituted ferroelectric Bi0.5Na0.5TiO3: An experimental study supported by Landau-Devonshire free-energy model based calculations

• Published in: Journal of applied physics 2020-03, Vol.127 (9)
• Main Authors: Kumari, Mukesh, Agarwal, Shubham, Santapuri, Sushma, Chatterjee, Ratnamala
• Format: Article
• Language: English
• ISSN: 0021-8979; 1089-7550
• DOI: 10.1063/1.5109827

This work presents an experimental and analytical study of a negative magnetoelectric (ME) effect observed in Fe substituted Bi0.5Na0.5TiO3 (BNT). Experiments are performed on solid solutions of Bi0.5Na0.5(FexTi(1 − 3x/4))O3 (BNFT), for x = 0 to 0.2, synthesized using the conventional solid state reaction route. X-ray diffraction studies confirm that Fe ions are completely soluble in a BNT matrix, up to the highest solubility of x = 0.2, thus forming a single-phase perovskite structure. As expected, partial substitution of Fe ions at Ti4+ sites diminishes the ferroelectric behavior of BNFT. For the optimal composition of x = 0.05, electrical poling of the sample results in an ∼19% decrease in magnetization, i.e., a large negative ME coupling is observed. Experimental results are supported by the Landau–Devonshire thermodynamic model based calculations for single-phase multiferroics. The model is utilized to obtain a theoretical estimate of the ME coupling coefficient of approximately −430 kV/cm Oe.