TORQUE MEASUREMENT OF MAGNETIC THIN-FILMS

The saturation magnetization Ms and the uniaxial anisotropy Ku of a thin magnetic film can be determined by means of torque measurement. Turning a magnetic film in a magnetic field H yields a plot of the torque L versus α, the angle between the normal of the film and the field direction. This plot contains a maximum L+m at an angle α+m and a minimum L-m at an angle α-m. Carrying out the above for an appropriate set of values of H, we can plot [(L+m-L- m)/2H]2 against 2 sin(α+ m-α-m)/(L+m-L -m)@qL. Ms and Ku are determined from the intercepts with the vertical and the horizontal axis, respectively, of the line obtained.