The AFM LAO lithography on GaMnAs layers

We prepared constrictions on ferromagnetic GaMnAs layer by the local anodic oxidation (LAO) using the atomic force microscope (AFM). These oxide lines, produced by the negatively biased AFM tip, formed the electrical barrier to the conducting holes in the layer. The constricted samples were characterized at low temperature (12 K). They showed magnetoresistance effect specific for nanoconstrictions during in-plane magnetic field sweep in both polarities for the different mutual orientation of magnetic field and current. The LAO appears to become a useful patterning technique for research of ferromagnetic semiconductor nanostructures. Further optimization of LAO parameters for reaching better homogeneity of the oxide lines is needed.