Laser activation of ferromagnetism in hydrogenated Ga1-x Mnx As

We demonstrate the local depassivation of hydrogenated Ga1-x Mnx As by pulsed-laser annealing. The controlled removal of Mn-H defect complexes, which form upon hydrogenation and render Mn acceptors inactive, is achieved by focused laser irradiation. As a result, regions of electrically and ferromagnetically active Ga1-x Mnx As are formed within a nonactive, otherwise structurally identical film. The hydrogenated films subjected to blanket laser depassivation display a Curie temperature TC up to 60 K, or 60% of the TC of the as-grown films. These results demonstrate the direct laser writing of mesoscopic ferromagnetically active regions as a viable route for the realization of planar, nanoscale spintronic systems.