Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe

MA: Fachverband Magnetismus

MA 39: Magnetic Thin Films

MA 39.6: Vortrag

Donnerstag, 20. März 2025, 16:30–16:45, H19

Ferrimagnetic moment arrangement in the Ti-doped Barium hexaferrite revealed by EMCD — •Hitoshi Makino¹, Devendra Singh Negi², Ján Rusz³, Bernd Rellinghaus¹, and Darius Pohl¹ — ¹DCN, TUD Dresden University of Technology — ²Indian Institute of Technology Jodhpur — ³Uppsala University

Barium hexaferrite is a well-known ferrimagnetic complex oxide with good durability at high temperatures and in erosive environments. Previous research has indicated that Titanium substitutions can enhance the coercivity at elevated temperatures. Our efforts aim at elucidating the underlying mechanism through measurements of electron energy loss magnetic chiral dichroism (EMCD) in the transmission electron microscope (TEM). We conducted EMCD experiments on three samples with different Titanium concentration (BaFe_12−xTi_xO₁₉, x=0, 0.6, 1.0). We have deconvoluted the Fe L-edges as obtained from classical EMCD measurements into different oxidation states of iron (Fe³⁺ → Fe²⁺ generated by Titanium-substitution) to observe the changing of magnetic moment arrangement. High resolution EELS mapping revealed, that Ti⁴⁺ ion substitute mainly for the 4f₂ site, an atomic site with parallel magnetic Fe moment. The EMCD signal of the Ti-rich sample (BaFe_12−xTi_xO₁₉, x=1.0) indicate an antiparallel Fe²⁺ magnetic moment arrangement. This discrepancy will be discussed by using inelastic scattering simulations as well as DFT calculations. A detailed analysis of the underlying measurement errors and the involved limitations of the method will be presented.

Keywords: EMCD; Barium hexaferrite; Ferrimagnetism; Electron energy loss spectroscopy; Transparent Electron Microscopy