Spinplasmonics: a new route for active plasmonics

In this paper we present a novel means of active control of a plasmonic system at the quantum level: the electron spin. Through manipulation of far infrared wavelength optical energy in the near-field, we experimentally show that electron spin can influence near-field mediated light propagation through a spintronic medium consisting of a dense ensemble of bimetallic ferromagnetic (F)/nonmagnetic(N) microparticles. The metallic medium under study is composed of ferromagnetic particles with nonmagnetic nano-layers, and it resembles a rudimentary spinplasmonic device that can be both optically and magnetically activated. Far infrared light transmission through the spinplasmonic medium shows very strong magnetic field dependent attenuation and optical phase retardation of the transmitted far infrared light pulses. The large attenuation is due to the interface resistance resulting from dynamic electron spin accumulation in N as spin-polarized electrons are optically driven from the F layer to the N layer. The demonstration of spin-dependent light propagation offers the basis for the development of novel devices and opens the door to a new field of spinplasmonics.