1. Laboratoire Charles Coulomb (L2C), UMR 5221 CNRS–Université de Montpellier, Montpellier, France
2. Institute for Physics of Microstructures, Russian Academy of Sciences, GSP-105, 603950 Nizhny Novgorod, Russia
3. Institut d'Electronique et des Systèmes (IES), UMR 5214 CNRS–Université de Montpellier, Montpellier, France
4. Institute of High Pressure Institute Physics, Polish Academy of Sciences, 01-447 Warsaw, Poland
5. Lobachevsky State University of Nizhny Novgorod, 603950 Nizhny Novgorod, Russia
6. Institute of Semiconductor Physics, Siberian Branch, Russian Academy of Sciences, pr. Akademika Lavrent'eva 13, 630090 Novosibirsk, Russia
7. Novosibirsk State University, 630090 Novosibirsk, Russia