Phase segregation and exchange biasing in TbFeCo films with perpendicular anisotropy

A TbFeCo film was deposited by DC magnetron sputtering and studied by transmission electron microscopy, polar and longitudinal magneto-optical Kerr effect, and magnetometry measurements. Transmission electron microscopy has shown the existence of lateral compositional inhomogeneity. Magneto-optical measurements have shown that the initial layer at the bottom consists of only magnetic perpendicular component and the top surface layer has a compositional inhomogeneity and consists of in-plane components and perpendicular one. The perpendicular components in the bottom and the surface layers have identical composition. Two in-plane components have been shown by magnetometry measurements. It is shown that phase segregation exists in the TbFeCo film and possible form of compositional inhomogeneity has been discussed. The two in-plane components are exchange coupled with a magnetization off-alignment of 35°. For the soft in-plane component, the in-plane and out-of-plane angular dependence of the exchange biasing is similar to those of the conventional one. Within temperatures from 100 to 300 K, the exchange field and the coercivity are both linear functions of temperature.