Anisotropic magnetization relaxation in ferromagnetic Ga1-xMnxAs thin films
Résumé
The magnetic properties of annealed, epitaxial Ga0.93Mn0.07As layers under tensile and compressive stress have been investigated by X-band (9 GHz) and Q-band (35 GHz) ferromagnetic resonance (FMR) spectroscopy. From the analysis of the linewidths of the uniform mode spectra the FMR Gilbert damping factor alpha has been determined. At T=4 K we obtain a minimum damping factor of alpha=0.003 for the compressively stressed layer. Its value is not isotropic. It has a minimum value for the easy axes orientations of the magnetic field and increases with the measuring temperature. Its average value is for both type of films on the order of 0.01 in spite of strong differences in the inhomogeneous linewidth which vary between 20 and 600 Oe for the layers grown on GaAs and GaInAs substrates, respectively.
Mots clés
annealing
compressive strength
damping
ferromagnetic materials
ferromagnetic relaxation
ferromagnetic resonance
gallium arsenide
III-V semiconductors
magnetic anisotropy
magnetic thin films
manganese compounds
semiconductor epitaxial layers
semimagnetic semiconductors
spectral line breadth
tensile strength