Rotomagnetic coupling in fine-grained multiferroic BiFeO3: Theory and experiment – Article 6

Abstract: Using Landau-Ginzburg-Devonshire (LGD) theory for BiFeO₃ dense fine-grained ceramics with quasispherical grains and nanosized intergrain spaces enriched by elastic defects, we calculated a surprisingly strong size-induced increase in the antiferromagnetic transition temperature caused by the joint action of rotomagnetic and magnetostrictive coupling. Notably, all parameters included in the LGD functional have been extracted from experiments, not assumed. Complementarily, we performed experiments for dense BiFeO₃ ceramics, which revealed that the shift of the antiferromagnetic transition is to T_N ∼ 690 K instead of T_N ∼ 645 K for a single crystal. To explain the result theoretically, we consider the possibility of controlling the antiferromagnetic state of multiferroic BiFeO₃ via biquadratic antiferrodistortive rotomagnetic, rotoelectric, magnetoelectric, and magnetostrictive couplings. According to our calculations, the highest contribution is the rotostriction contribution, while the magnetostrictive and electrostriction contributions appear smaller.

Title: Rotomagnetic coupling in fine-grained multiferroic BiFeO₃: Theory and experiment

Authors: Anna N. Morozovska, Eugene A. Eliseev, Maya D. Glinchuk, Olena M. Fesenko, Vladimir V. Shvartsman, Venkatraman Gopalan, Maxim V. Silibin, and Dmitry V. Karpinsky

DOI: https://doi.org/10.1103/PhysRevB.97.134115   Physical Review B (2018) 97, 134115

Preprint deposited in the repository: https://arxiv.org/abs/1803.02805