Vertical spin transport in Al with Pd/Al/Ni80Fe20 trilayer films at room temperature by spin pumping

Spin pumping enables the vertical transport of pure spin current throughAl in a Pd/Al/Ni80Fe20(Py) trilayer film, inwhich the Py acts as a spin battery. The spin current injected into the Al flows through theAl to reach the Pd, resulting in the generation of electromotive forces due to the inverse spin Hall effect in the Pd. The electromotive forces decreased with increasing thickness of the Al layer. A simplemodel based on the theory by Tserkovnyak et al., allows an estimation of the spin coherence of the vertical spin transport in the Al of 61 nm. This comparatively short coherence is attributed to a reduction in spin pumping efficiency because of the roughness of the Al/Py interface.