Magnetization dynamics in microscopic spin-valve elements: Shortcomings of the macrospin picture

Article

关键词: PHOTOEMISSION ELECTRON-MICROSCOPY;    MAGNETORESISTANCE;    EXCHANGE;    DEVICES;    LAYERS;    FIELD;   

DOI  :  10.1103/PhysRevB.76.134410

来源: SCIE

【 摘 要 】

We have studied ultrafast magnetodynamics in micropatterned spin-valve structures using time-resolved x-ray photoemission electron microscopy combined with x-ray magnetic circular dichroism. Exciting the system with ultrafast field pulses of 250 ps width, we find the dynamic response of the free layer to fall into two distinctly different contributions. On the one hand, it exhibits localized spin wave modes that strongly depend on the shape of the micropattern. A field pulse applied perpendicular to the exchange bias field along the diagonal of a square pattern leads to the excitation of a standing spin wave mode with two nodes along the field direction. This mode is strongly suppressed for a pattern of elliptical shape. On the other hand, the integrated response of the free layer roughly follows a single-spin model with a damping constant of alpha=0.025 independent of the shape and resembles the response of a critically damped forced oscillator.

【 授权许可】

Free