1. Institute of Micro- and Nanostructure Research (IMN), Center for Nanoanalysis and Electron Microscopy (CENEM), Interdisciplinary Center for Nanostructured Films (IZNF), Friedrich-Alexander-Universität Erlangen-Nürnberg, 91058 Erlangen, Germany
2. Max Planck Institute for Intelligent Systems, 70569 Stuttgart, Germany