Spin Relaxation Enhanced by Decorating Cu Surfaces With Lead (II) Phthalocyanine Molecules

We have investigated spin relaxation and spin-to-charge conversion at the Cu surface decorated with lead (II) phthalocyanine (PbPc) molecules. The study on the frequency dependence of ferromagnetic resonance linewidth revealed that the Cu/PbPc interface exhibits more pronounced spin relaxation than that of the Cu/H2Pc (metal-free phthalocyanine) interface. A clear peak owing to the spin-to-charge conversion was observed in the spin-pumping-induced voltage spectrum for a NiFe/Cu/PbPc trilayer film, whereas no trace of peak was observed in the film with NiFe/Cu/H2Pc. These results might be attributed to the Rashba effect at Cu surface by the decoration with PbPc, which indicates the new possibility of molecular spintronics.