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 Karl Franzens University Graz

Graz University of Technology 

Mapping Orbital Information in the TEM
Stefan Löffler
University Service Centre for Transmission Electron Microscopy, TU Wien, Austria
16:15 - 17:15 Tuesday 12 January 2021 remote online presentation via Webex

Electronic states shape the world around us and are typically described in terms of orbitals. These orbitals as well as their complex interactions with each other and with external fields define material properties both on the atomic and on the macroscopic scale. Be it chemical bonding, optical, magnetic or mechanical material properties — they all can be traced back to the interplay of orbitals. Despite their importance, however, there are only very limited possibilities of investigating these orbitals directly so far.
In this work, I will present several methods based on transmission electron microscopy (TEM) and electron energy-loss spectrometry (EELS) to directly probe orbital properties such as their orientation, size, and spin state inside a sample. All these methods rely on measuring and interpreting the complex energy spectrum as well as the position and momentum distributions of an electron beam that has undergone inelastic scattering inside the sample. In particular, the focus will be on core-loss scattering, i.e., the electron beam triggering a transition from a tightly-bound (“core”) electron to the conduction band.