Oxygen‐vacancy‐controlled magnetic properties with magnetic pole inversion in BiFeO₃‐based multiferroics

Abstract

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 BiFeO3 (BFO)‐based system. The BiFeO3‐DyFeO3 (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 Dy3+ 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 Fe3+ 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.

Structural, electrical, and magnetic study of La-, Eu-, and Er- doped bismuth ferrite nanomaterials obtained by solution combustion synthesis

“…There are a few possible reasons for such discrepancy between most of the literature data and the experimental values obtained in this work. For instance, the concentration of oxygen vacancies in the structure of the obtained BFO was reported to influence the magnetisation of Dy-doped BFO 75 . The increasing number of oxygen vacancies could lead to the overall enhancement in the magnetisation of BFO-based nanomaterials, as it promotes an increase in the amount of Fe 2+ to Fe 3+ ions transitions for compensation of excess positive charge.…”

Aliovalent Calcium Substitution: An Effective Way to Enhance the Magnetoelectric Coupling Properties of Multiferroic BiFeO3

“…The lower binding energy peak (here it is 526.61, 527.92, and 530.18 eV, respectively, for BCFO-00, BCFO-10, and BCFO-20) can be assigned to metal oxygen bond; higher binding energy peak with components positioned at 528.41, 530.19, and 531.88 eV can be attributed to oxygen atoms in the vicinity of an oxygen vacancy. [42,43] The percentage of oxygen vacancy concentration has been calculated according to the ratio of HB to LB. The percentage of concentration of oxygen vacancy calculated is 58.18%, 14.76%, and 49.09% for BCFO-00, BCFO-10, and BCFO-20, respectively.…”

Effects of Multiple Local Environments on Electron Energy Loss Spectra of Epitaxial Perovskite Interfaces

“…1,2 Interestingly, effects such as diffusion, 3 point defects (including vacancies), 4,5 and strain gradients 6−9 are now deliberately introduced to modify the electronic structure and induce (and tune) new functionalities in multiferroic thin films such as electrochemically induced strain 10 and oxygenvacancy-controlled magnetism. 11 The development of such engineered multiferroic thin films, as well as other novel functional interfaces, 12 has relied on their characterization by electron microscopy techniques, 13−15 in particular, through the combination of scanning transmission electron microscopy (STEM) and electron energy loss spectroscopy (EELS), where unprecedented spatial and energy resolution can now be achieved (<1 Å and 15 meV). 16 Coreloss EELS is highly sensitive to local crystallographic, chemical, and electronic structural changes, while low-loss EELS can provide information on the optical response and band gap of materials.…”

“…Interestingly, effects such as diffusion, point defects (including vacancies), , and strain gradients − are now deliberately introduced to modify the electronic structure and induce (and tune) new functionalities in multiferroic thin films such as electrochemically induced strain and oxygen-vacancy-controlled magnetism …”