1. Institute of Physics, Polish Academy of Sciences, Al. Lotników 32/46, 02-668 Warszawa, Poland
2. Department of Physics, Technical University, Malczewskiego 29, 26-600 Radom, Poland
3. Equipe de Physique de l'Etat Condensé, URA CNRS 807, Université du Maine, 72017 Le Mans, France