| Affiliation: | 1. Max-Planck-Institut für Mikrostrukturphysik, Weinberg 2, D-06120 Halle, Germany;2. Department of physics, Indian Institute for technology-Roorkee, 247667 Uttarkhand, India;1. Department of Mathematics, Beihang University, District Shahe Higher Education Park South Third Street No. 9, Beijing 102206, PR China;2. Department of Mathematics, Purdue University, West Lafayette, IN 47907, USA;3. School of Mathematical Sciences, Beijing Normal University, Haidian District Xinjiekou Waidajie No. 19, Beijing 100875, PR China |
