Magnetic Domains in the Ferromagnetic Semiconductor (Ga,Mn)(As,P)

GaMnAs is a model system for diluted ferromagnetic semiconductors. The origin of ferromagnetism is the exchange interaction between the carriers and the Mn 3d spins with exchange constant Jpd. The phosphorous alloying of GaMnAs is used as a novel practical technique to adjust the magnetic anisotropy. It provides layers with perpendicular anisotropy with high homogeneity. The spin-stiffness constant A is determined and the field-driven domain wall dynamics is investigated using Kerr microscopy. In GaMnAsP due to the low density of defects the magnetic domains form a self-organized pattern. From its period the spin-stiffness constant A and the first neighbor effective exchange energy JMnMn are determined. JMnMn is larger than in GaMnAs. This result along with the higher spin-wave stiffness in GaMnAsP might indicate that the Jpd value is higher in GaMnAsP than in GaMnAs. The temperature dependence of A is experimentally determined and compared to the theoretical predictions. The field-driven domain wall dynamics is studied in GaMnAsP and GaMnAs.The domain wall undergoes a flexion and twist therefore the experimental velocity curves deviate from the theoretical 1D model.

Autorentext

Dr. Sanaz Haghgou has obtained her PhD degree in Solid-state Physics in 2012. She had graduated in Bachelor's degree from Tehran Polytechnic University (AUT) and continued her study in UPMC Sorbonne University of Paris where she has got her PhD degree. During her PhD project she contributed in several international conferences.