| The effect of magnetization reversal, with longitudinal fields, on the resistance of anisotropic magnetoresistance (AMR) thin film permalloy is explored. This reversal produces a “chirp” like response: other researchers refer to the phenomena as flipping, magnetization reversal and switching field. The applied magnetic field is swept from negative to positive, and back to negative along the length of the resistor, the easy axis, producing a complex resistance change that exhibits hysteresis. The research literature discusses the change in resistance of some materials by an externally applied magnetic field. In the case of permalloy, a field applied orthogonal to the resistor direction produces a change of resistance which is the cosine squared of the angle deviation of the internally rotated field. The existing research suggests a field applied along the length of the resistor produces no change in resistance or that the value of the change of resistance is comparatively small. The cos2 of 180 degrees is the same as cos2 of 0 degrees, therefore, no change in resistance is measured with a field along the resistor length. This research shows the change of resistance of thin film permalloy resistors, with magnetic fields along the mechanical length of the resistor, can be significant. The work proposed shows a new approach to modelling the resistance during magnetization reversal with easy axis applied field. The measurements were performed on resistors of thickness 50–385 Angstroms, and 6–50 μm wide. |
