1. Pushkov Institute of Terrestrial Magnetism; Ionosphere and Radio Wave Propagation (IZMIRAN); Russian Academy of Sciences; Kaluzhskoe sh. 4 142190 Troitsk Moscow Russia
2. Magnetic and Cryoelectronic Systems Ltd.; IZMIRAN, Kaluzhskoe sh. 4; 142190 Troitsk Moscow Russia
3. Moscow State Institute of Radio Engineering; Electronics and Automation (MIREA); Prospekt Vernadskogo 78 119454 Moscow Russia
4. Dpto. de Fisica de Materiales; Fac. Químicas; Universidad del Pais Vasco; 20018 San Sebastián Spain
5. IKERBASQUE; Basque Foundation for Science; 48011 Bilbao Spain