MICROMAGNETIC SCANNING MICROPROBE SYSTEM

We describe the apparatus, instrumentation, and data acquisition techniques which make up the micromagnetic scanning microprobe system (MSMS). This system Was developed to study magnetoresistive (MR) thin films used in magnetic recording read heads. Et uses a de, four-probe resistance measurement coupled with two pairs of orthogonal field sources. Voltage contacts to the thin film are made with microprobe tips 0.1 mu m in diameter on local edge and central regions of the film. Horizontal and vertical microscopes are used to verify tip placement. Results from magnetoresistance measurements of the dynamic response of a MR read head film are shown to demonstrate system operation and performance. The bulk and local magnetoresistance of a 10 mu m X 10 mu m NiFe thin film was measured as a function of applied field and angle. Significant variations in MR responses were seen across the width of the device because of local domain formation. The MSMS is an effective tool for characterizing the effects of domain formation on the output of a MR read head.