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MA: Fachverband Magnetismus

MA 39: Magnetic Thin Films

MA 39.7: Vortrag

Donnerstag, 20. März 2025, 16:45–17:00, H19

Imaging Local Magnetic Moments with Atomic-Scale Electron Vortex Beams via EMCD in BaFe₁₁TiO₁₉ — •Darius Pohl¹, Hitoshi Makino¹, Bernd Rellinghaus¹, Rolf Erni³, Devendra Singh Negi⁵, Arthur Ernst⁴, and Ján Rusz² — ¹DCN, TUD Dresden University of Technology, Dresden, Germany — ²Uppsala University, Uppsala, Sweden — ³Empa, Dübendorf, Switzerland — ⁴JKU, Lenz, Austria — ⁵Indian Institute of Technology Jodhpur

Electron magnetic circular dichroism (EMCD), the electron wave counterpart of X-ray magnetic circular dichroism (XMCD), enables element-specific measurement of spin and orbital magnetic moments with nanometer-scale resolution in transmission electron microscopy. Electron vortex beams (EVBs), recently discovered to carry quantized orbital angular momentum (OAM), are emerging as a promising tool for EMCD measurements, facilitating the analysis of magnetic properties in materials. Since EVBs can be tightly focused to sub-nanometer scales, this approach offers unprecedented potential for quantifying spin and orbital magnetic moments with exceptional spatial resolution. We employ specially designed condenser apertures to produce isolated, atomic-scale EVBs with user-defined OAM. As a proof-of-concept, we demonstrate vortex EMCD measurements on ferrimagnetic barium hexaferrite samples. For the first time, EVB-EMCD achieves the resolution necessary to resolve local ferrimagnetic order. The experimental findings are further corroborated by inelastic scattering simulations and density functional theory (DFT) calculations.

Keywords: Ferrimagnet; EMCD; TEM