Enhancement of thermoelectric performance of a nanoribbon made of α-Τ₃ lattice.

We present electronic and transport properties of a zigzag nanoribbon made of $\alpha-\mathcal{T}_3$
 lattice. Our particular focus is on the effects of the continuous evolution of the edge modes (
 from flat to dispersive) on the thermoelectric transport properties. Unlike the case of graphene
 nanoribbon, the zigzag nanoribbon of $\alpha-\mathcal{T}_3$ lattice can host a pair of 
 dispersive (chiral) edge modes at the two valleys for specific width of the ribbon.
 Moreover, gap opening can also occur at the two valleys depending on the width. The slope
 of the chiral edge modes and the energy gap strongly depend on the relative strength of two
 kinds of hoping parameters present in the system. We compute corresponding transport
 coefficients such as conductance, thermopower, thermal conductance and the thermoelectric
 figure of merits by using the tight-binding Green function formalism, in order to explore
 the roles of the dispersive edge modes. It is found that the thermopower and thermoelectric
 figure of merits can be enhanced significantly by suitably controlling the edge modes.
 The figure of merits can be enhanced by thirty times under suitable parameter regime in
 comparison to the case of graphene. Finally, we reveal that the presence of line defect, 
 close to the edge, can cause a significant impact on the edge modes as well as on electrical
 conductance and thermopower.