Giant spin Hall conductivity in platinum at room temperature

Abstract

We have demonstrated the electrical generation and detection of spin polarization by the spin Hall effect (SHE) in platinum. The experiment was performed in a non-local geometry without the use of ferromagnetic materials or magnetic field. We designed a circuit that uses the SHE to convert a charge current to a spin current, and the inverse SHE to convert the spin current back into a charge signal. The experiments were carried out for temperatures from 10 K up to 290 K. We extracted the spin Hall conductivity and spin diffusion length from the data with the aid of a spin diffusion model, and found the values of 1.1 $\times 10^6$ $\Omega^{-1}$m$^{-1}$ and 80~nm, respectively, at 290 K. The spin Hall conductivity is two orders of magnitudes larger than the previous record of $3.3\times10^4$ $\Omega^{-1}$m$^{-1}$. This observation may have many potential applications in spintronics devices.