1. Faculty
of Materials Science and Engineering, Kunming University of Science and Technology, Kunming 650093, China
2. National
Center for Electron Microscopy in Beijing, School of Materials Science
and Engineering, Tsinghua University, Beijing 100084, China
3. Department
of Materials Science and Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
4. Ernst
Ruska-Centre for Microscopy and Spectroscopy with Electrons and Peter
Grünberg Institute, Forschungszentrum Jülich, 52425 Jülich, Germany
5. School of
Materials Science and Engineering, Beihang University, Beijing 100191, China