Magnetic properties of amorphous FeC thin films

Abstract

Thin films of amorphous FexC1-x (0. 75≤x≤0.50) were prepared by sputter deposition. Room temperature values for 4πMs ranged from 13000 gauss (x=0.75) to 6500 gauss (x=0.50). Thus the room temperature magnetization is much higher than that for amorphous alloys of Fe with other group IV elements. The increased magnetization appears to be due to a higher Curie temperature as well as a larger atomic moment. It is well known that bulk amorphous samples of rapidly quenched alloys of transition metals with group III, IV and V elements can be prepared with low Hc; however, little is known of the properties of these alloys when prepared with thin films. We show that amorphous films of FeC can be prepared as Hc≈0.10 Oe without the need for post deposition annealing by proper selection of deposition parameters, in particular the argon gas pressure. The anisotropy energy is also dependent upon deposition gas presssure, going to zero for the same pressure that produces low Hc. Magnetostriction measurements have been made, and the films have large positive magnetostriction (Λ≈+1.5×10-5) which decreases with C content.