Abstract: Multiferroic materials are a key element in the drive for technological advances. Materials that exhibit magnetoelectric coupling, where the magnetic state can be controlled with an electric field and vice versa, are of particular interest due to their potential role in the field of electronics. However, fully exploiting such materials and their properties requires deeper knowledge of the underlying magnetic and electronic interactions than we currently possess.
The ε-phase of Fe2O3 is intriguing because it is a hard ferrimagnet with strong magnetoelectric coupling at room temperature.[1] As it contains only a single species of cation, ε-Fe2O3 avoids some of the composition and stoichiometry challenges of similar perovskite oxides such as BiFeO3.[2] However, such simplicity comes at a cost. Because each of the four structural sites contain only Fe3+ ions, decoupling their interactions is not straightforward. As a result, creative approaches are necessary to better understand this unique phase.
In this talk I will discuss the advantages of using variety of techniques (soft XAS/XMCD, EXAFS, Mössbauer spectroscopy) to examine ε-Fe2O3 and transition metal-doped ε-Fe2O3 nanoparticles. By identifying how the transition metal dopant ions serve to perturb the crystal and electronic structure of the parent phase we gain new insights into the Fe-O-Fe interactions of ε-Fe2O3. These results indicate that dynamic electronic interactions between neighbouring tetrahedral Fe sites play a significant role in this unique material’s most interesting properties.
[1] M. Gich et al. Nanotechnology, 2006, 17, 687.
[2] L. Dedon et al. Chem. Mater, 2016, 28, 5952.