Role of finite-size effect in BiFeO3 nanoparticles to enhance ferromagnetism and microwave absorption

Exploring the performance of nanoscale multiferroic materials is a significant challenge because the physical properties of these materials vary dramatically on this scale. In the present work, BiFeO3 (BFO) nanoparticles are synthesized by a facile sol-gel method, producing homogeneous spherical nanoparticles whose Raman modes and binding energies coincide with pure rhombohedral perovskite BFO. The dramatic magnetic properties of nanoscale BFO with diameters in the range of 50-130nm are explored by analyzing the temperature and field dependence of magnetization, and detailed zero-field cooling and field cooling magnetization curves show that interparticle interactions play a constructive role in increasing the magnetic response. Moreover, BFO nanoparticles have two absorption regions in the range of 2-18GHz, and the minimum reflection loss is -18dB. The finite-size effect is discussed as the primary mechanism for enhancing the ferromagnetism and microwave absorption, and the results provide a feasible route for designing multifunctional materials.