Oxygen‐vacancy‐controlled magnetic properties with magnetic pole inversion in BiFeO 3 ‐based multiferroics

Oxygen vacancies which are generally present in ferrite oxide may significantly affect their magnetic properties. A comprehensive understanding of the relationship between oxygen vacancies and magnetism is of great importance. In this work, we report an oxygen vacancy concentration dependence of magnetism in a single‐phase multiferroic BiFeO 3 (BFO)‐based system. The BiFeO 3 ‐DyFeO 3 (BDFO) solid solution is synthesized with controlled oxygen vacancies and is characterized by X‐ray powder diffraction (XRD), X‐ray photoelectron spectroscopy (XPS), and AC impedance spectroscopy. The magnetic properties, especially magnetic pole inversion, are found to be highly dependent on oxygen vacancy concentration. The oxygen vacancies generate a Weiss molecular field on the Dy 3+ ions in the magnetic field range of 570‐1000 Oe depending on the oxygen vacancy concentration, and result in a residual net magnetization by breaking the balance between the two nearly antiparallel spin lattices of Fe 3+ ions. This work demonstrates an effective way to control oxygen vacancies and thereby the magnetic properties and sheds light on the relationship between oxygen vacancies and magnetism in BFO‐based multiferroics.