MAGNETOOPTICAL MEASUREMENT OF ANISOTROPY ENERGY CONSTANTS ON AMORPHOUS RARE-EARTH TRANSITION-METAL ALLOYS

Measurements of the magneto-optic polar Kerr effect are performed on samples with perpendicular magnetization using in-plane magnetic fields. The magnetic anistropy constants are then determined from these measurements. The applied in-plane magnetic field varies from -20 to 20 kOe. Samples are mounted in a temperature-controlled chamber whose temperature is varied in the range of 80-475 K. In the theoretical model the anisotropy energy is expressed as the sum of terms containing sin2 φ and sin4 φ with two anisotropy constants, K1 and K2, to be determined. By matching the theoretical curves with the experimental data, we obtain two functions α(T) and β(T), which are the normalized values of K 1(T) and K2(T) with respect to the saturation magnetization Ms(T).