Electronic, magnetic and transport properties of silicene armchair nanoribbons substituted with monomer and dimer of Fe atom

This study employed density functional theory calculations to investigate the structural, electronic and magnetic properties of an armchair silicene nanoribbon (ASiNR) substituted with a monomer and a dimer of Fe atom. As a result, the direct band gap of pristine ASiNR turns into a smaller indirect band gap by substituting an Fe atom in the proper position. The magnetic moment of doped Fe reduces and the structure keeps its nonmagnetic property. The substitution of the Fe-dimer can change the pristine ASiNR from a nonmagnetic semiconductor to a magnetic half-metal, which is favorable for spintronic devices. Two external electric fields were applied to the structure substituted with the Fe-dimer and electronic properties were studied in this situation. It was shown that the Fe-dimer substituted ASiNR is such a versatile material that a band gap can be tuned by using an external transverse electric field. Furthermore, the transport properties of these two structures were studied with non-equilibrium Greens function formalism. It is intriguing that single-spin negative differential resistance was observed in the Fe-dimer doped ASiNR.