1. Institute
of Materials Physics, University of Goettingen, Friedrich-Hund-Platz 1, 37077 Goettingen, Germany
2. Center
for Electron Nanoscopy, Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark
3. Helmholtz-Zentrum
Berlin for Materials and Energy, Hahn-Meitner-Platz
1, 14109 Berlin, Germany
4. National
Center for Electron Microscopy, MS 72-150, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
5. Department
of Condensed Matter Physics and Materials Science/Center for Functional
Nanomaterials, Brookhaven National Laboratory, Upton, New York 11973, United States