Ferromagnetic resonance in (Ga,Mn)As

Abstract Dilute magnetic semiconductors exhibit unique magnetic and transport properties which arise from the coupling of carrier spins and local moments. We have studied the ferromagnetic resonance spectra in ferromagnetic Mn-doped GaAs (with Mn concentrations ∼4–6%), whose properties are strongly influenced by this coupling. The resonance fields were found to have an anomalous temperature dependence, which we attribute to the development of a “bottleneck” between the two types of spins. The gyromagnetic ratio of hole spins in this p-type ferromagnetic semiconductor was found to be negative, with g∼−0.5. At low temperatures, additional anisotropy appears, which we have attributed to the trapping of itinerant holes by the core spins.