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MM: Fachverband Metall- und Materialphysik
MM 42: Electron Microscopy II - Advances in characterisation
MM 42.2: Vortrag
Mittwoch, 2. April 2014, 12:15–12:30, IFW B
Feasibility study of using electron vortices for the measurement of electron magnetic circular dichroism (EMCD) — •Sebastian Schneider1,2, Darius Pohl1, Ludwig Schultz1,2, and Bernd Rellinghaus1 — 1IFW Dresden, Institute for Metallic Materials, P.O. Box 270116, D-01171 Dresden, Germany — 2TU Dresden, Institut fur Festkörperphysik, D-01062 Dresden, Germany
EMCD, which is the electron wave analogue of X-ray magnetic circular dichroism (XMCD), offers the possibility to study magnetic properties on the nanoscale in a transmission electron microscope (TEM). Re- cently discovered electron vortex beams, which carry an orbital angular momentum, are assumed to show comparable dichroic signals. This study is focused on the feasibility of this newly discovered method. Dichroic signals on the L2 and L3 edges of 3d transition metals are expected to be of the order of only 5%. In order to measure such small intensity changes in the electron energy loss (EEL) spectra, a proper microscope alignment, highly stable samples, and a high signal-to-noise-ratio of the EEL spectra are indispensable. Neglecting any of these preconditions will easily lead to artifacts showing a mime of a dichroic signal already in the raw data of the EELS spectra. Different types of magnetic samples are investigated and probed for the appearance of a dichroic signal thereby always paying highest attention to accurate measurements to avoid boosting any signals without physical relevance to EMCD. For this, thin ferromagnetic films of Fe, Fe3C and Ni are prepared by sputtering and investigated with this novel method.