Patterning of epitaxial MnAs on GaAs by direct optical writing

We demonstrate patterning of ferromagnetic MnAs layers on GaAs substrates b y optical writing with a focused laser beam. Depending on the writing condi tions, stripes with ridge- and groove-shaped cross sections can be produced without damage of the GaAs substrate. Using in situ control by resistance measurements, conditions for the preparation of completely insulating strip es can be established. The formation of insulating and paramagnetic Mn3O4 d uring optical writing is verified by Raman scattering. (C) 2001 American In stitute of Physics.