Spin transport properties in a naphthyl diamine derivative film investigated by the spin pumping

TL;DR

This study demonstrates efficient spin transport in a naphthyl diamine derivative film using spin pumping and inverse spin-Hall effect, revealing a long spin diffusion length suitable for spintronic applications.

Contribution

First experimental demonstration of spin transport in alpha-NPD film via spin pumping and ISHE, with a measured spin diffusion length of 62 nm at room temperature.

Findings

Spin current generated in alpha-NPD by FMR in Ni80Fe20.

Inverse spin-Hall effect observed in Pd layer confirms spin transport.

Estimated spin diffusion length of 62 nm at room temperature.

Abstract

We report the spin transport properties in a thin film of a naphthyl diamine derivative: N,N'-Bis(naphthalen-1-yl)-N,N'-bis(phenyl)-2,2'-dimethylbenzidine (alpha-NPD). In a palladium(Pd)/alpha-NPD/Ni80Fe20 tri-layer structure sample, a pure spin current is generated in the alpha-NPD layer with the spin pumping driven by ferromagnetic resonance (FMR). The generated spin current is absorbed into the Pd layer, and converted into a charge current with the inverse spin-Hall effect (ISHE) in Pd. An electromotive force due to the ISHE in the Pd layer is observed under the FMR of the Ni80Fe20 layer, which is clear evidence for the spin transport in an alpha-NPD film. The spin diffusion length in an alpha-NPD film is estimated to be about 62 nm at room temperature, which is long enough as a spin transport material for spintronic devices.