Highly Bi-doped Cu thin films with large spin-mixing conductance

The spin Hall effect (SHE) provides an efficient tool for the production of pure spin currents, essentially for the next generation of spintronics devices. Giant SHE has been reported in Cu doped with 0.5% Bi grown by sputtering, and larger values are predicted for larger Bi doping. In this work, we demonstrate the possibility of doping Cu with up to 10% of Bi atoms without evidence of Bi surface segregation or cluster formation. In addition, YIG/BiCu structures have been grown, showing a spin mixing conductance larger that the one shown by similar Pt/YIG structures, reflecting the potentiality of these new materials.