A hysteresis model for an orthogonal thin-film magnetometer

The operation of a ferromagnetic thin-film magnetometer using the anisotropic magnetoresistance effect in a permalloy film is discussed. Measurements showed the presence of a hysteresis effect not predicted by available models. It is shown that the sensitivity of the magnetometer is predicted by applying F.S. Greene and R.B. Yarbrough's (1970) orthogonal susceptibility model, and that the hysteresis can be explained by assuming dispersion in the magnitude of anisotropy. The orthogonal susceptibility model must be evaluated numerically, accounting for a finite driving field. The effect of an inhomogeneous demagnetizing field in the film is discussed in relation to magnitude dispersion of the anisotropy.< >