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

Abstract

The anomalous Hall coefficient (Rs) and longitudinal resistivity (Ï xx) scaling relationship (RS=cÏ xxn) 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 1 eV. These atypical behaviors are characteristic of spherical resonance from metallic inclusions.