Elsevier, Physica B: Condensed Matter, (401-402), p. 447-450
DOI: 10.1016/j.physb.2007.08.208
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We demonstrate two patterning techniques based on hydrogen passivation of Ga1−xMnxAs to produce isolated ferromagnetically active regions embedded uniformly in a paramagnetic, insulating host. The first method consists of selective hydrogenation of Ga1−xMnxAs by lithographic masking. Magnetotransport measurements of Hall-bars made in this manner display the characteristic properties of the hole-mediated ferromagnetic phase, which result from good pattern isolation. Arrays of Ga1−xMnxAs dots as small as 250nm across have been realized by this process. The second process consists of blanket hydrogenation of Ga1−xMnxAs followed by local reactivation using confined low-power pulsed-laser annealing. Conductance imaging reveals local electrical reactivation of micrometer-sized regions that accompanies the restoration of ferromagnetism. The spatial resolution achievable with this method can potentially reach