Defect induced room temperature ferromagnetism in lead-free ferroelectric Bi0.5K0.5TiO3 materials

Development the multiferroic materials based on the lead-free ferroelectric materials is the new possible channel to create the next generation devices. The pure Bi0.5K0.5TiO3 and Mn-doped Bi0.5K0.5TiO3 materials were synthesized using sol-gel method. While the substitution of Mn for Ti site reduces the optical band gap in Bi0.5K0.5TiO3, the room temperature ferromagnetism is obtained in both un-doped and Mn-doped Bi0.5K0.5TiO3 materials. By means of the first-principles calculations, the ferromagnetism in Mn-doped Bi0.5K0.5TiO3 materials can be explained by the mixed valence states of Mn ions through the crystal field mechanism and that in un-doped Bi0.5K0.5TiO3 materials is ascribed to the formation of O or Ti vacancies during the sample growth.