Effect of thermal annealing of high temperature growth [(GaAs) m (Fe) n ] p composite films on GaAs(001) by molecular beam epitaxy

Abstract

GaAs) m (Fe) n ] p composite films on GaAs(001) substrates obtained by molecular beam deposition methods at T s = 580°C have been thermally annealed, and magnetic/structural changes caused by the annealing have been measured to study the relation between room-temperature photo-magnetic effect and by-products in composite films. Annealing inhomogeneous [(GaAs) 8 (Fe) 5 ] 20 film, prepared by alternate beam deposition of Fe and GaAs, results in an increase in saturation magnetization, whereas the room-temperature photo-enhanced magnetization (RT-PEM) vanishes. Metamagnetic Fe 3 Ga 4 is suppressed with the formation of ferromagnetic Fe 3 Ga 2-x As x . Observed results suggest two important points : firstly, metamagnetic Fe 3 Ga 4 compound is most likely meta-stable bi-product and may play a principle role for RT-PEM, and secondly, ferromagnetic Fe 3 GaAs and its derivatives are the stable form in Ga-As-Fe ternary system.