The thesis was supervised by Dr. Florencio Sánchez Barrera and Dr. Josep Fontcuberta i Griñó (MULFOX group). The PhD committee was formed by Dra. Marina Tyunina (University of Oulu, Finland; Institute of Physics, Prague, Czech Republic), Dr. José Angel Pardo Gracia (University of Zaragoza, Spain) and Dr. Wilfrid Prellier (CRISMAT, CNRS, France).