Observation of disorder induced crossover in the underlying mechanism for the anomalous Hall Effect and intrinsic spin currents in Ga1-xMnxAs

Here, we report on the transport and Hall measurements on a series of Ga_1-xMn_xAs where we explicitly control the total Mn concentration (NMn) during low temperature molecular beam epitaxy (LT-MBE) growth and implicitly control group III substitutional Mn concentration (NMn) by low temperature annealing. After growth, monitored by in situ RHEED, and NMrl determined by HRXRD and EPMA, a series of Ga_1-xMn_xAs epilayers were patterned into Hall bars utilizing standard photolithographic techniques as well as citric acid/hydrogen peroxide-based standard GaAs etchant and annealed in a flowing N₂ environment in a tube furnace for an hour with annealing temperature varied from 200-350 degC as monitored near the sample.