Giant spin-charge conversion driven by nanoscopic particles of Ag in Pt

Abstract

We report the observation of a giant enhancement in the interconversion efficiency between spin current and charge current by the spin Hall effect made possible with the use of nanoscopic structures of Ag in a Pt layer. We fabricate heterostructures of yttrium iron garnet (YIG)/Pt, in which nanoparticles of Ag were grown in the midplane of the Pt layer. These nanostructures serve as nanoscopic molds that enhance the local spin orbit coupling by means of the Rashba effect at the Pt-Ag interfaces. The effective spin Hall angle in YIG/[Pt (3 nm)-Ag (9 nm)]/Pt (3 nm) is determined to be in the range of 27--40%, which is about one order of magnitude larger than the spin Hall angle of pure Pt, typically in the range of 2--8%. The results were confirmed by means of three different experimental techniques, namely spin pumping effect, spin Seebeck effect, and spin Hall magnetoresistance. We believe that this important discovery will contribute to advance the development of spin-based technology.