Dual function armchair graphene nanoribbon-based spin-photodetector: Optical spin-valve and light helicity detector

We show an armchair graphene nanoribbon channel connected between asymmetric ferromagnetic source-drain structure-i.e., p-type Co/Au/graphene source and n-type Co/Cu/graphene drain-can operate as dual function spin-photodetector, under zero external biases at room temperature. It can function as an optical spin-valve with magnetoresistance of greater than 60% and responsivity as high as 25.12 A/mW, when irradiated by an un-polarized light of energy similar to 3.03 eV. Under a circularly polarized illumination, this optical spin-valve can also operate as a light helicity detector. The calculated magnetoresistances for right and left circularly polarized lights are both greater than 60%. (C) 2014 AIP Publishing LLC.