FABRICATION AND MAGNETIZATION MEASUREMENTS OF VARIABLE-PITCH GRATINGSOF COBALT ON GAAS

A technique for engineering micron and sub-micron scale structures fro m magnetic films of transition metals has been developed using a combi nation of electron and ion beam lithography. The pattern is defined by a mask produced by 60kV electron beam lithography, enabling near-vert ical sidewalls to be produced. The focused ion beam is rastered to etc h cobalt in the mask openings. PMMA and aluminium masks have been asse ssed. High quality arrays of magnetic Co wires have been fabricated on GaAs substrates. This processing is adaptable to the fabrication of n ovel devices from a variety of metal combinations which would not be p ossible by the usual lift-off metallisation route. An artificial shape anisotropy is observed in the magnetic properties of gratings of widt h approximately 0.5mum and separation 0.5mum fabricated from a 50nm th ick Co film, resulting in a demagnetising field of approximately 0.8ke mptysete.