Electricity: measuring and testing – Magnetic – Magnetometers
Patent
1996-06-05
1998-05-05
O'Shea, Sandra L.
Electricity: measuring and testing
Magnetic
Magnetometers
338 38R, 33318, 33355R, G01R 3309, G01C 1700
Patent
active
057479976
ABSTRACT:
The present invention provides a method and apparatus for utilizing spin valve magnetoresistance devices for the measurement of weak magnetic fields. The magnetoresistive element consists of a pinned ferromagnetic layer and a soft ferromagnetic layer separated by a thin spacer layer. The pinned layer may be pinned by high intrinsic coercivity, or by a neighboring antiferromagnet or high coercivity ferromagnet layer. An oscillating magnetic field is applied to the device. The amplitude of the excitation field is large enough to reverse the magnetization of the soft layer during each cycle, but small enough that the magnetization direction of the pinned layer is not much affected. In one embodiment, the applied field is applied using a current strip deposited onto the top of the other layers, so that the entire device can be produced on a single chip.
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Dahlberg E. Dan
Moran Timothy J.
O'Shea Sandra L.
Patidar Jay M.
Regents of the University of Minnesota
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