Thermoelectric effects in silicene nanoribbons

Abstract

Transport and thermoelectric coefficients (including also spin thermopower) of silicene nanoribbons with zigzag edges are investigated by ab-initio numerical methods. Local spin density of such nanoribbons reveals edge magnetism. Like in graphene, one finds antiferromagnetic and ferromagnetic ordering, with spin polarization at one edge antiparallel or parallel to that at the other edge, respectively. Thermoelectric properties, especially the Seebeck coefficient, significantly depend on the electronic band structure and are enhanced when the Fermi level is in the energy gap. However, these thermoelectric properties are significantly reduced when the phonon contribution to the heat conductance is included. This phonon contribution has been calculated numerically by two different methods. Transition from antiferromagnetic to ferromagnetic states leads to a large magnetoresistance as well as to a considerable magnetothermopower. Thermoelectric parameters in the antiparallel configuration, when spin polarization in the left part of the nanoribbon is opposite to that in the right part, are also analyzed.

Thermoelectric Properties of Doped Zigzag Silicene Nanoribbons

“…Very recently, thermoelectric phenomena in SiNRs have been studied in both pristine [5] and doped nanoribbons [8]. The subject is of current interest due to the possibility of converting dissipated heat to electrical energy at nanoscale.…”

“…Quasi-one-dimensional silicene nanoribbons (SiNRs) have also been fabricated [3], and their electronic as well as magnetic and mechanical properties have been extensively studied by ab-initio methods [4,5]. Silicene nanoribbons can exhibit semiconducting or metallic character, similarly to graphene ones.…”

Design for a spin-Seebeck diode based on two-dimensional materials

“…The electronic structure of silicene from ab inito calculations is similar to that of graphene 14 , both have high electric conductivity. However, silicene is not strictly planar but has a buckled structure with a height difference ∆ between adjacent Si atoms of about 0.46Å 15,16 , which leads to a nonzero energy gap and remarkably enhances Seebeck coefficient 17,18 . To realize SSD, we need to have magnetic ZSiNR, which typically can be done through doping 19 , defects 20 and edge-modification 21 .…”

Zigzag nanoribbons of two-dimensional silicene-like crystals: magnetic, topological and thermoelectric properties

“…In fact, thermoelectric properties of nanoribbons have been studied theoretically in a couple of papers. [38][39][40][41][42] However, the role of Coulomb interaction and topological edge states in the gap, has not been studied thoroughly enough yet. In a recent paper 43 we have analyzed the influence of topological states on the thermoelectric properties, with the main focus on the role of a staggered exchange field [5][6][7] and of an electric field perpendicular to the atomic plane.…”