CrPtMn顶钉扎自旋阀材料的交换耦合作用研究

Exchange Coupling in CrPtMn-based Top-pinning Spin Valves

反铁磁钉扎层和铁磁被钉扎层之间的交换耦合作用是高性能自旋阀材料研究中的一个关键因素。本工作研究了CrPtMn顶钉扎自旋阀材料中的交换耦合场(Hex)与薄膜沉积条件以及退火处理之间的关系。研究表明:沉积后的自旋阀材料中的Hex大小与CrPtMn钉扎层的溅射工作气压关系不大,Hex约为7.96×103A/m。然而,经过240℃退火2 h处理后,Hex呈现出与CrPtMn沉积时的溅射工作气压相关的特性,随着溅射工作气压的增加而增大。材料退火后的交换耦合场Hex的温度特性良好,室温下约为2.39×104A/m。Hex随着测试温度的升高而逐渐减小,交换耦合场消失时的失效温度(blocking temperature)为315℃。

The exchange coupling effect between the ferromagnetic pinned layer and antiferromagnetic pinning layer is considered to be one of the key factors for fabricating high performance spin-valves. In this study, the dependence of the exchange coupling field （Hex） in CrPtMn-based spin valves on the deposition pressure and subsequent anneal treatment has been investigated. It is found that the Hex for the as-deposited spin valves changes little by varying the sputtering pressure during the deposition of the CrPtMn pinning layer, and the Hex value is roughly 7.96 × 10^3 A/re. However, after the as-deposited spin valves are annealed at 240 ℃ for 2 h, the Hex correlates and increases with an in- crease of the sputtering pressure during the CrPtMn deposition. The exchange coupling Hex for annealed spirt valves shows good thermal stability with a strength of 2.39 × 10^4 A/m at room temperature. The Hex gradually decreases with increasing temperature, and finally disappears at 315 ℃ which is its blocking temperature.