1. Sorbonne Université, CNRS, Laboratoire de Physique Théorique de la Matière Condensée, LPTMC, F-75005 Paris, France
2. St. Petersburg State University, 7/9 Universitetskaya nab., St. Petersburg 199034, Russia
3. Department of Physics, Lappeenranta University of Technology, 53850 Lappeenranta, Finland