The Effect Of Stress Field On Properties Of Thin Magnetic Films

The perpendicular record is considered to be one of the most promising technologies in magnetic record. In order to understand the properties of the magnetic materials, induce the perpendicular anisotropy of magnetic thin films, we studied the effect of the stress field which has an angle with the film on the properties of the ferromagnetic resonance and the direction of magnetization.First, it is showed that the effect of the stress field on the ferromagnetic resonance frequency when the stress field changed in the plane which is perpendicular to the film plane. Numerical calculations show that both the value and direction of stress field affect the direction of easy or hard axis when the applied field H and stress field are in the same plane. However, when the applied field H is in the thin ferromagnetic film plane, the direction of easy or hard axis will be independent from the stress field. When both applied field and stress field are perpendicular to the film plane, it is found that if H_λ< 4πM /3, the value of resonance frequency will retain zero for low applied filed, else if H_λ> 4πM/3, the value of the resonance frequency will present discontinuously in critical field. In addition, it is found that the value of the critical field and saturation field are strongly affected by the direction and magnitude of stress field. Second, in order to make a further understanding that the effect of stress field on magnetization of film, it is shown that the relation of the direction of the easy axis vs stress field, when the applied field and stress field both are in the plane which is perpendicular to the films. Numerical calculations show that the stress field also affects the direction of the easy or hard axis. For a given value, if the stress field changes near by the perpendicular direction of the film plane, the affect is stronger. When the stress field is perpendicular to the film, it get to a value, the magnetization of film will change from in-plane to perpendicular.The effect of the stress field and exchange anisotropy field on perpendicular magnetization in ferromagnetic/antiferromagnetic bilayers is investigated by using ferromagnetic resonance method. It is shown that the stress anisotropy has strong effect on the easy/hard axis and the extent of easy/hard magnetization. The enhancement of the stress which is perpendicular to the film will accelerate the perpendicular magnetization and block the parallel magnetization, even change the magnetization from in-plane to perpendicular. Furthermore, the perpendicular exchange coupling can lead to unidirectional anisotropy, which can also accelerate the perpendicular magnetziation.