Static and Dynamic Magnetic Domains of Epitaxial gamma -Fe4N Thin Films

Abstract

Highly-ordered single-phase thin films of gamma'-Fe4N were deposited by dc magnetron sputtering directly on single-crystal MgO(100) substrates at different temperatures. The surface morphology showed that a very regular nano-sized grain structure gradually turned into a smooth layered growth with increasing temperature tip to 450 degrees C. The minimum root-mean-square value of the surface roughness was achieved after 30 minutes in-situ annealing at 450 degrees C. The epitaxial texture of the films was revealed by X-ray diffractometry Bi-axial in-plane magnetic anisotropy, characteristic of strong ferromagnetism, was observed from the quite squarish M-H loops obtained with the help of a vibrating sample magnetometer Bow-tieshaped static domain patterns and a very dense domain structure were direct evidence of strong exchange coupling among magnetic domains. Time-resolved dynamic magnetic domain patterns were observed in gamma'-Fe4N thin films by using a magneto-optic microscope magnetometer.