Wavelength-selective spin-current generator using infrared plasmonic metamaterials

A subwavelength plasmonic absorber is an ideal platform for absorbing light locally at a desired wavelength. Here, we demonstrate wavelength-selective spin current generation by combining plasmonic absorbers with Pt/yttrium-iron-garnet spintronic devices. These devices are widely used for investigating spin-current phenomena, such as the spin Seebeck effect. At the resonance of the plasmonic absorber in the mid-infrared regime, enhanced spin-current signals are recorded. The observed light-induced spin current can be attributed to both the spin Seebeck effect and photo-spin-voltaic effect. Our results open new prospects for using plasmonic absorbers to bridge nanophotonics and spintronics in numbers of opto-spintronic applications.