Magneto-optical measurement of anisotropy energy constant(s) for amorphous rare earth, transition metal alloys

Measurements of the anisotropy energy constants of rare-earth-transition-metal (RE-TM) thin films at temperatures from ambient to 150°C are reported. An in-plane magnetic field (up to 16.5 kOe) is applied to a saturated sample with perpendicular magnetization. The movement of magnetization away from the perpendicular direction is monitored using the polar Kerr effect. Due to the limited penetration depth of light at the He-Ne wavelength of 632.8 nm, the Kerr effect is principally due to the top 500 Å of the transition metal subnetwork in the films