交流バイアス磁界を用いた高感度GMRセンサ

概要

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In this paper, we propose a new sensitive magneticsensor consisting of a multilayered structure that includes a NiO spin-valve element and an Ac bias current line.The spin-valve element, patterned to a microscopicsize, exhivits a step-shaped magnetoresistive (MR) loop in which a free-layer magnetization switches like a single domain.High sensitivity is obtained by only the (rising or falling) edge of the Mr LOOP.An AC bias magnetic field induced by a square-wave bias current (plus or minus) was applied to the spin-valve element. The bias magnetic field was set to be slightly smaller than the rising field. The resistance of the spin-valve element is con-stant, if an external magnetic field is not applied.The output signal synchronizes with the input bias current, if the vias field is made to cross the rising edge of the MR loop by applying an external magnetic fiel.Our magnetic sensor detects an external field change of 0.5Oe.A highperfprmance magnetic sensor can obtained by monitoring the switshing value shange in a ramp-shaped bias current in which the strength continuously shanges. The direction and value of the slight change in the external magnetic field were measured with high resolution.
社団法人日本磁気学会の論文
1998-04-15