Thermoelectric properties of zigzag silicene nanoribbons doped with Co impurity atoms

• Thermoelectric properties of silicene nanoribbons doped with Co adatoms.
• The adatoms influence the corresponding electronic bandstructure.
• Two magnetic orderings are possible.
• In the ferrimagnetic state a large spin thermopower can occur.
• In the ferromagnetic state both thermopowers are rather moderate.

Thermoelectric properties of silicene nanoribbons doped with Co adatoms located in the edge positions are investigated theoretically by ab initio numerical methods based on the density functional theory. The adatoms are shown to considerably influence the corresponding electronic band structure, which results in two different magnetic states of the nanoribbons – ferrimagnetic with semiconducting transport properties and ferromagnetic of metallic character. In the former state magnetic moments at the two edges are antiparallel, while in the latter case they are parallel. Numerical calculations show that a significant spin thermopower can occur in the ferrimagnetic state due to a non-zero band-gap, while in the ferromagnetic state both conventional and spin thermopowers are rather moderate. Thus, the ferrimagnetic state arising due to the presence of impurities at the edge positions appears to be the most appropriate from the point of view of spin thermoelectric phenomena.