Evidence of metallic clustering in annealed Ga1−xMnxAs from atypical scaling behavior of the anomalous Hall coefficient

The anomalous Hall coefficient (Rs) and longitudinal resistivity (ρxx) scaling relationship (RS=cρxxn) for a series of annealed Ga1−xMnxAs epilayers (x≈0.055) are investigated. As-grown samples exhibit a scaling parameter n∼1 and samples annealing near the optimal annealing temperature, n∼2. For annealing temperatures far above the optimum they observe scaling with n>3, which is similar to the behavior of certain inhomogeneous systems. Optical spectroscopy measurements also reveal an enhancement of the absorption coefficient in these samples for photons of energy around 1eV. These atypical behaviors are characteristic of spherical resonance from metallic inclusions.