Thermoelectric effects in silicene nanoribbons

Abstract

Transport and thermoelectric coefficients (including also spin thermopower)\nof silicene nanoribbons with zigzag edges are investigated by {\\it ab-initio}\nnumerical methods. Local spin density of such nanoribbons reveals edge\nmagnetism. Like in graphene, one finds antiferromagnetic and ferromagnetic\nordering, with spin polarization at one edge antiparallel or parallel to that\nat the other edge, respectively. Thermoelectric properties, especially the\nSeebeck coefficient, significantly depend on the electronic band structure and\nare enhanced when the Fermi level is in the energy gap. However, these\nthermoelectric properties are significantly reduced when the phonon\ncontribution to the heat conductance is included. This phonon contribution has\nbeen calculated numerically by two different methods. Transition from\nantiferromagnetic to ferromagnetic states leads to a large magnetoresistance as\nwell as to a considerable magnetothermopower. Thermoelectric parameters in the\nantiparallel configuration, when spin polarization in the left part of the\nnanoribbon is opposite to that in the right part, are also analyzed.\n