Fundamental research on Hall effects in inhomogeneous magnetic fields

The fundamental physics of the Hall effect in locally inverted inhomogeneous magnetic fields are investigated theoretically and experimentally; and the design, fabrication, and operation of micron-scale three-terminal InSb and GaAs monocrystal Hall elements are reported. The directionality of Hall-element galvanomagnetic detectors and their sensitivity to field inhomogeneities are demonstrated, and applications using single elements or arrays with magnetic-bubble domains are described. The InSb and GaAs elements fabricated have size 5 and 4 microns square, active thickness 2.6 and 1 micron, sensitivity 140 V/A T and 500 V/A T, and maximum signal-to-noise ratio 145 and 104 dB, respectively. Applications include direct mapping of stray magnetic fields from magnetic domains in a magnetic-bubble film, magnetic-bubble detection in 100-micron and 5-10-micron domains, direct measurement of domain velocity, and displacement sensing. Graphs, diagrams, photographs, and drawings are provided.