Carbon atomic chains in a spin thermoelectric device

Abstract

We investigated spin-dependent thermoelectric properties of a carbon atomic chain (CAC) between two zigzag-edged triangular graphene nanoflakes (GNFs), with two semi-infinite armchair graphene nanoribbons (AGNRs) as the electrodes. Using the non-equilibrium Green’s function method combined with the effective selfconsistent mean-field Hubbard approximation, we found that the designed configuration shows large thermo-spin effects that could be tuned by the gate voltage, chemical potential as well as temperature. Our results show that the non-magnetic AGNRs with the edge magnetism of the GNFs and CAC located between them induces a notable spin Seebeck coefficient (SSC), comparable to or more than that in zigzag graphene nanoribbon junctions, for all sizes of CAC. Finally, applying a gate voltage and a temperature gradient across the chain-based caloritronic device could induce a pure spin current, a perfect spin filtering effect, and an unrivaled negative differential thermal resistance in a broad range of temperatures close to room temperature.