Mapping three-dimensional atomic order in rare earth iron garnets
Tuesday, February 6, 2024
11 a.m. — 11:45 a.m. ET
Allison Kaczmarek, PhD Candidate
Materials Science & Engineering, MIT
Complex oxides offer rich magnetic and electronic behavior intimately tied to the composition and arrangement of cations within the structure. When a crystallographic site is populated by more than one type of ion, ordering of those ions can dramatically affect the material properties. Rare earth iron garnets are a class of ferrimagnetic complex oxides with extraordinary properties, making them essential materials for microwave and optical devices. Thin films of these materials exhibit a magnetic anisotropy along the growth direction which has long been believed, but not proven, to originate from the ordering of rare earth cations on dodecahedral sites.
In this presentation, Kaczmarek will discuss how researchers uncovered the three-dimensional ordering of rare earth ions in films of europium thulium iron garnet using both X-ray diffraction and atomically resolved elemental mapping, specifically by aberration-corrected scanning transmission electron microscopy (STEM). Further, they quantified the resulting ordering-induced ‘magnetotaxial’ anisotropy as a function of Eu:Tm ratio. By solving this 50-year-old mystery, researchers have demonstrated that site ordering provides a powerful strategy to control matter on the atomic level and to augment the magnetic properties of complex oxides.
Attendees can join and participate in the series via Zoom.