Decreased oxygen vacancies and improved ferroelectric properties of the BiFeO3 thin films with high magnetic field annealing

Abstract

High magnetic field annealing (MFA) effects on polycrystalline BiFeO3 (BFO) thin films deposited on ITO buffered glass substrates by the chemical solution deposition (CSD) method have been investigated. Magnetic force induced by magnetic field leads to the increased crystallite size and the decrease in activation energy for boundary motion, especially for the low temperature annealed films. More Fe3+ ions are induced with increasing magnetic field to lower the free energy of the BFO films, which also leads to a decreased oxygen vacancy, resulting in low leakage current density. The increased remanent polarization and the decreased coercive field initially with the increase in magnetic field are attributed to the reduced domain wall pinning resulted from decreased oxygen vacancies and grain boundaries. Generally, the decreased coercivity and the improved ferroelectric polarization suggest high MFA is an effective way to enhance ferroelectric properties of the CSD-derived BiFeO3 thin films.