Spin Hall effects in mesoscopic Pt films with high resistivity

TL;DR

This study demonstrates that increasing the resistivity of mesoscopic platinum films enhances spin Hall effects, with detailed measurements revealing a significant spin Hall angle product and a short spin diffusion length.

Contribution

The paper provides a quantitative analysis of spin Hall effects in high-resistivity mesoscopic Pt films, revealing an upper limit for spin diffusion length and demonstrating enhanced SHE in these conditions.

Findings

Enhanced SHE observed in high-resistivity Pt films.

Spin diffusion length in Pt is less than 0.8 nm.

The product of spin Hall angle and spin diffusion length is approximately 0.142 nm.

Abstract

The energy efficiency of the spin Hall effects (SHE) can be enhanced if the electrical conductivity is decreased without sacrificing the spin Hall conductivity. The resistivity of Pt films can be increased to 150-300 {\mu}{\Omega}*cm by mesoscopic lateral confinement, thereby decreasing the conductivity. The SHE and inverse spin Hall effects (ISHE) in these mesoscopic Pt films are explored at 10 K by using the nonlocal spin injection/detection method. All relevant physical quantities are determined in-situ on the same substrate, and a quantitative approach is developed to characterize all processes effectively. Extensive measurements with various Pt thickness values reveal an upper limit for the Pt spin diffusion length: {\lambda}_pt<0.8 nm. The average product of {\lambda}_pt and the Pt spin Hall angle {\alpha}_H is substantial: {\alpha}_H*{\lambda}_pt=(0.142 +/- 0.040)nm for 4 nm thick Pt, though a gradual decrease is observed at larger Pt thickness. The results suggest enhanced spin Hall effects in resistive mesoscopic Pt films.