Local magnetoresistance and point‐source excitation of Ni‐Fe thin films (abstract)

The magnetoresistive (MR) response was measured in Ni‐Fe thin films, representative of the films used in magnetic recording read heads, with sense areas as small as 6×6 μm. For the bulk, central, and edge regions of the film, the MR response was measured as a function of magnitude and angle of a uniform in‐plane applied magnetic field. Measurements were made using a four‐contact technique which included two scanning microprobes and two orthogonal field sources. The microprobes could be scanned with a resolution of 0.1 μm and positioned separately. The field sources produced a maximum field of 24 kA/m (300 Oe) that could be rotated up to ±15°. From the local MR response, the local magnetic behavior was obtained and compared to micromagnetic theory. The bulk MR response was also measured as a function of position on the film of a microfield source used for point‐source excitation. The microfield source was a Fe wire electrochemically etched to a 0.1 μm tip diameter. From these results the local MR sensitivi...