ω−2ω transition in a chevron stretcher detector

The ω−2ω transition1 in the magnetoresistance waveform at 100 KHz was investigated for a long Permalloy chevron stretcher detector in the absence of bubbles propagating through the structure. When the Permalloy is demagnetized by decreasing the rotating inplane field, H, in the absence of any dc fields, the waveform of the resistance variation is 2ω for 0angular frequency of rotation. When the Permalloy is ac demagnetized in the presence of a small dc field applied along the long axis of the detector element, the resulting waveform has an ω dependence for 0phase angles of the rotating inplane field at which resistance maxima occur depend on the direction in which the dc field was applied during demagnetization. A domain model based on magnetization fanning is proposed to explain these results.