A relatively new field of investigation is molecular spintronics, in which magnetic molecular junctions are used as spin transport channels [1]. Both experiments and theoretical works suggest that organic materials can offer similar and perhaps superior performances in making spin-devices than the more conventional inorganic metals and semiconductors [2]. Among organic materials, porphyrins are considered promising candidates because they offer a variety of desirable features such as highly conjugated structure, rigid planar geometry and good chemical stability [3]. In this work we study by first principles the transport properties of a magnetic molecular junction consisting of Fe-porphyrin molecule connected with two semi-infinite graphene electrodes. The calculations were performed using the TranSIESTA code [4], which combines the non-equilibrium Green's function (NEGF) technique with DFT. We find that the localized Fe states do not produce relevant effects on the current which in fact displays only a slight polarization. We further investigate the electron transport through the same molecular junction contacted with boron and nitrogen doped graphene electrodes. The presence of the dopants leads to a non negligible density of states around the Fermi level allowing the hybridization between iron and carbon states. In the case of B-doped electrodes a current polarization is observed, while in the N-doped case a Negative Differential Resistance effect can be pointed out. With differently doped electrodes, one with boron and the other with nitrogen, the junction displays a partial rectification behavior. Since the electronic properties of the metal atom can be modulated by the adsorption of a gas molecule, we study the effect of a gas molecule adsorption on the charge transport and we observe a quenching of the current polarization in the B-doped system. References [1] A.R. Rocha et al., Nature Mater. 5 335 (2005) [2] S. Sanvito, Nature Mater. 6 803 (2007) [3] S.U. Lee et al., Small 7 962 (2008) [4] M. Brandbyge et al., Phys. Rev. B 65 165401 (2002)
Electron transport in a Fe-Porphyrin/graphene junction
MI Trioni;F Cargnoni;R Soave
2017
Abstract
A relatively new field of investigation is molecular spintronics, in which magnetic molecular junctions are used as spin transport channels [1]. Both experiments and theoretical works suggest that organic materials can offer similar and perhaps superior performances in making spin-devices than the more conventional inorganic metals and semiconductors [2]. Among organic materials, porphyrins are considered promising candidates because they offer a variety of desirable features such as highly conjugated structure, rigid planar geometry and good chemical stability [3]. In this work we study by first principles the transport properties of a magnetic molecular junction consisting of Fe-porphyrin molecule connected with two semi-infinite graphene electrodes. The calculations were performed using the TranSIESTA code [4], which combines the non-equilibrium Green's function (NEGF) technique with DFT. We find that the localized Fe states do not produce relevant effects on the current which in fact displays only a slight polarization. We further investigate the electron transport through the same molecular junction contacted with boron and nitrogen doped graphene electrodes. The presence of the dopants leads to a non negligible density of states around the Fermi level allowing the hybridization between iron and carbon states. In the case of B-doped electrodes a current polarization is observed, while in the N-doped case a Negative Differential Resistance effect can be pointed out. With differently doped electrodes, one with boron and the other with nitrogen, the junction displays a partial rectification behavior. Since the electronic properties of the metal atom can be modulated by the adsorption of a gas molecule, we study the effect of a gas molecule adsorption on the charge transport and we observe a quenching of the current polarization in the B-doped system. References [1] A.R. Rocha et al., Nature Mater. 5 335 (2005) [2] S. Sanvito, Nature Mater. 6 803 (2007) [3] S.U. Lee et al., Small 7 962 (2008) [4] M. Brandbyge et al., Phys. Rev. B 65 165401 (2002)I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
