Magnetization reversal mechanism of ultra thin Nd_2Fe_(14)B films with perpendicular magnetic anisotropy

摘要

The crystallographic and magnetic properties of sub-10-nm Nd_2Fe_(14)B films have been investigated. It is found that the magnetization reversal mechanism is changed in Nd-Fe-B films with the decrease of film thickness. Films with thickness greater than 10 nm show domain-wall-motion type of behavior. Strong exchange coupling between the grains makes the magnetic domain wall easily propagate in the films. Films with thickness of 4 nm show the Stoner-Wohlfarth particle behavior. The initial magnetization process is magnetization rotation. This is also verified by angular dependence of the coercivity.