Magnetic anisotropy of Ir-doped CrO2

Ir-doped CrO2particles were prepared. Their magnetic properties are described. Remanence coercivities, HR, up to 270 kA/m were obtained. From measurements of the initial reversible susceptibility, Xrev, and from particle geometry data the magnetocrystalline anisotropy field, HK, was calculated. With increasing Ir-content HKraises up to 530 kA/m. The experimental relationship between the remanence coercivity and the magnetocrystalline anisotropy field can be well fitted by the theoretical equation HR=0.529H.K. From this it is concluded that the magnetization reversal is predominantly rotation in unison. Within the composition range of up to 5% Ir, the Curie temperature decreases from 125°C of the undoped material to 110°C.