Structure and magnetic properties of compositionally modulated Tb-Fe thin films

Abstract

Amorphous Tb-Fe compositionally modulated films (CMFs) with alternating ultrathin Tb and Fe layers were sequentially deposited in a multitarget r.f. diode sputtering system. All of the Tb-Fe CMFs, except those with small Tb content, exhibited a large perpendicular anistropy. Compared with alloy films, the Tb-Fe CMFs exhibited anomalous structural and magnetic properties such as a compensation composition with increased Tb content, higher Curie temperatures, and an extension in the composition range of stable amorphous films to higher Tb contents. The atomic arrangements in this layered structure were modified by a variation of deposition parameters such as layer periodicity, substrate bias and composition. The primary factor responsible for the anomalies appeared to be the alignment of a strong atomic Tb-Tb and Fe-Fe pair distribution in the layers of the CMF.