Abstract

We report on experimental and theoretical evidence of a ferromagnetic phase in the diluted semiconductor CuGa_1-xMn_xTe₂ using the Ferromagnetic Resonance (FMR) technique. The FMR spectra were studied as functions of temperature (T) manganese concentration (x) and magnetic field orientation. The samples were synthesized by direct fusion of the stoichiometric mixture of the elements, with Mn composition from x=0.05 to 0.25. The data were interpreted in the framework of a phenomenological model for single domain uniaxial grains. The temperature variation of the resonance field shows a critical point at about 230K, which is associated with a transition from the ferromagnetic to paramagnetic state. This behaviour is explained assuming an effective magnetization following the exponential law M(T)/M(O)=(1-T/T_C)^β, with β≈0.40. The resonance field as a function of the field angle displays a well-defined uniaxial symmetry at high Mn concentrations. This uniaxial field is Mn concentration dependent and is due to the formation of ovoid Mn grains with G-factor greater than 3.0.

Keywords:Magnetic semiconductors; Magnetic anisotropies; Ferromagnetic resonance; Diluted ferromagnets