The present invention relates to a magnetic device. The magnetic device includes: a free layer including a first magnetization layer; a pinned layer including a second magnetization layer; and a tunnel barrier layer interposed between the free layer and the pinned layer. At least one from the first magnetization layer and the second magnetization layer comprises includes a composite antiferromagnetic layer structure composed of a first ferromagnetic layer, a second ferromagnetic layer, and a Ru-Rh alloyed layer interposed between the first ferromagnetic layer and the second ferromagnetic layer.
