Conductance Parametric Analysis of Graphene Nanoribbons With Magnetic Contacts

Graphene nanoribbons with non-magnetic contacts have been extensively studied and are widely used in graphene based devices. In these devices, the nanoribbon conductance is modulated and controlled by applying potentials through top and back gates. Graphene nanoribbons with magnetic contacts have been studied and used as spin valves, mostly at liquid-helium temperatures. The operation of graphene nanoribbons with magnetic contacts at room temperature, where nanoelectronic devices and circuits are expected to operate, has received little attention. Here we study and simulate the operation of graphene nanoribbons with magnetic contacts using tight-binding Hamiltonians and the non-equilibrium Green's functions(NEGF) method, which we extend to incorporate the effect of magnetic contacts. Our results are in very good agreement with experimental measurements of the conductance of graphene nanoribbons with NiFe ferromagnetic contacts. We also perform extensive parametric analysis of the dependence of the nanoribbon conductance on the relative orientations of the contact magnetic polarizations, combined with potentials applied through top and back gates. Our results revealed a very rich parametric space that can be exploited to develop multifunctional platforms which, among others, can be used for digital, analog and neuromorphic computations.