1. Physikalisches Institut, Westfälische Wilhelms-Universität, 48149 Münster, Germany
2. Center for Nanotechnology, 48149 Münster, Germany
3. Center for Quantum Joint Studies and Department of Physics, Tianjin University, Tianjin, China
4. Department of Physics and Beijing Key Laboratory of Optoelectronic Functional Materials & Micro-Nano Devices, Renmin University of China, Beijing, China
5. Center for Multiscale Theory and Computation, 48149 Münster, Germany