Novel torque magnetometry for uniaxial anisotropy constants of thin films and its application to FePt granular thin films

A technique based on torque magnetometry is proposed for precise determination of the uniaxial magnetic anisotropy constant, K-u, of perpendicularly magnetized thin films, in particular for K-u larger than 10(6) J/m(3), by electrical detection of the anomalous Hall effect and exact determination of the magnetic field direction. This technique can measure the K-u value of several-nanometer-thick polycrystalline films. Further, the K-u value of FePt-C granular films, which are expected to be useful for high-density magnetic recording media, is evaluated. The intrinsic K-u value of 4-nm-thick FePt-C thin films fabricated at 450 degrees C is approximately 3 MJ/m(3) for carbon contents up to 34 vol% C. (C) 2018 The Japan Society of Applied Physics