Giant spin thermoelectric efficiency in ferromagnetic graphene nanoribbons with antidots

Abstract

Thermoelectric effects in zigzag graphene nanoribbons with parallel alignment of the edge spin polarizations are investigated theoretically. Spin and charge thermopower, electrical and heat conductance, and charge and spin thermoelectric efficiency are calculated numerically for pristine nanoribbons as well as for nanoribbons with periodic one-dimensional lattice of structural defects in the form of antidots. It is shown that structural defects reduce thermal conductance due to phonons and open gaps in the corresponding electronic spectrum. This, in turn, leads to a significant enhancement of the Seebeck and spin Seebeck coefficients as well as of the thermoelectric efficiency. A giant enhancement appears in certain regions of chemical potential (controlled by doping or external gate) and survives at room temperatures.