Résumé
During the last decade, considerable experimental and theoretical efforts have been devoted tothe study of GaMnAs semiconductors due to their high ferromagnetic transition; "Curie temperature (Tc)" and their interesting magnetic properties. The potential implementation of structures based on GaMnAs diluted magnetic semiconductors as spintronic devices needs solid understanding of magnetic anisotropy and magnetization reversal processes. Nowadays, it is well established that the ferromagnetic interaction between magnetic ions is mediated by charge carriers, holes in this case. However, defects such as As antisites and Mn interstitials play a crucial role in determining the magnetic properties of GaMnAs. The objective of this study is to investigate the magnetic properties and anisotropy using magnetotransport measurements as well as the dynamics domain wall by high resolution magneto-optical imaging. Predicted theoretical models and developed ones by our team are in good agreement with experimental data. Finally, in this work, we emphasize the first evidence by transport measurements of two in-plane uniaxial axis reorientations. Another part of the talk will focus on new potential applications using magnetic multilayers structures to detect very small field, down to nanotesla, to investigate magnetic properties of spin-crossover materials