Evaluation of Magnetic Anisotropy of RE-TM Thermomagnetic Recording Films by the Measurement of Hall Hysteresis Loop Under Obliquely Applied Magnetic Field

A new method is proposed for checking the magnetic anisotropy of rare earth-transition metal amorphous alloy films for magneto-optical recording. The Hall loop is measured when the magnetic field H is applied to the film at an inclination angle ¿(measured relative to the normal of the film), and the relationship between the loop coercivity Hc ´ and ¿, the angle of orientation of H in the film plane, is plotted in polar coordinates. From theoretical considerations, if the film has an obliquely directed magnetic anisotropy, then the shape of the Hc ´- ¿ plot should be elliptical. If the measured Hc ´- ¿ plot is indeed elliptical, then the direction of the magnetic easy axis of the film can be calculated using equations presented in this paper.