Patrick Rush Webb

Orthogonal pinning of two ferromagnetic layers in a synthetic spin valve

A method for pinning synthetic antiferromagnet (SAF) based spin valves is presented, which allows pinning to be established perpendicular to the setting field H. As the SAF(AP1/Ru/AP2) magnetizes, its layer moments undergo a spin–flop transition for a magnetic field H=HSF and align with H for H=HSat. The magnetization of layer AP1 is perpendicular to H for a field H=HGold. This field corresponds to the maximum giant magnetoresistance GMR on HSF<H<HSat for an unpinned SAF spin valve. SAF-pinned samples [antiferromagnet/AP1/Ru/AP2] set using H=HGold are mixed domain, with AP1 magnetized in two directions perpendicular to H, corresponding to left- and right-handed flopping. The spin–flop handedness may be controlled for a viable process. The technique offers substantial advantages to sensor stabilization schemes that rely on additional pinned ferromagnet/antiferromagnet layers, because these layers may be pinned orthogonal to the SAF without regard to the blocking temperatures of the respective antiferromagnets.