Regensburg 2010 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 12: FS: Single Nanomagnets

MA 12.2: Topical Talk

Dienstag, 23. März 2010, 11:15–11:45, H22

Magnetic chirality in the electron microscope: Progress and Applications — •Peter Schattschneider — Inst. F. Festkörperphysik und Univ. Serviceeinrichtung für Elektronenmikroskopie, Technische Universität Wien, A-1040 Vienna, Austria

Via the electron-electron interaction it can be shown everything that can be done in a synchrotron is also feasible in an electron microscope. In practice, however, electron and photon probes behave differently. In this respect, the EMCD technique (energy loss magnetic chiral dichroism) in the electron microscope [1] - the equivalent of the synchrotron based XMCD, a standard technique for the study of atom specific magnetism - has the intrinsic advantage of high spatial resolution. The main difficulty with EMCD is the low signal intensity, asking for exposure times of the order of minutes, and very particular scattering conditions necessary to observe a chiral dichroic signal. Nevertheless, much progress was made in the last years. EMCD has evolved into several techniques, now utilising either energy filtering, spectroscopy, TEM or STEM conditions. After a synopsis of the present situation in EMCD, recent results such as nanometric resolution, the applicability of XMCD sum rules, and new image simulation software are discussed. The observation that chiral electronic transitions break certain mirror symmetries in energy spectroscopic diffraction (ESD) led to the prediction that this chirality pertains in energy filtered high resolution imaging, thus opening a road to mapping electron spins of individual atomic columns under HR-TEM conditions. [1] P. Schattschneider et al., Nature. 441 (2006), 486.