The role of metallic nanoparticles in the enhancement of the spin Hall magnetoresistance in YIG/Pt thin films

Enhancements in the spin Hall magnetoresistance (SMR) close to one order of magnitude in bilayers of yttrium iron garnet (YIG) and platinum with embedded metallic nanoparticles of Ag and Cu are reported. The enhancement in the electrical detection of the back reflected spin current in YIG/Pt-MP(tMP)-Pt relative to YIG/Pt is attributed to the increase in the effective spin Hall angle (θSHAeff) due to the presence of the metallic nanoparticles. The maximum value observed for the spin Hall magnetoresistance is related to critical thickness of the tMP close to the percolation threshold. The results are also supported by data obtained by means of the spin pumping effect where dc-voltage measurements confirm the enhancement of the spin to charge conversion process.