Measurement of magnetic anisotropy constant for magneto-optical recording media: A comparison of several techniques

Abstract

Experimental data of the intrinsic perpendicular magnetic anisotropy energy constant Ku are presented for amorphous rare earth-transition metal (RE-TM) Tbx(FeCo)1−x and multilayered Co/Pt thin film samples. These data were independently measured using five techniques based on torque magnetometry, the extraordinary Hall effect, and the magneto-optic Kerr effect. In the Hall effect measurement, the external field was applied to the sample in three different ways: fixed at 45° from the film normal; rotating around the sample; and fixed along the in-plane direction. The results obtained with these techniques agree with each other for the Co/Pt samples. However, we do find systematic differences in the measured Ku for the Tbx(FeCo)1−x samples. For example, Ku given by the Hall effect and Kerr effect is always larger (by up to a factor of 3) than that given by torque technique. Another interesting fact is that Ku given by the Hall effect technique drops as x approaches the compensation point xc in the TM-dominant case, but increases as x approaches xc in the RE-dominant case. These experimental results are explained by taking into account the canting between RE and TM subnetworks.