"Pudding mold" band drives large thermopower in Na${}_x$CoO${}_2$

Abstract

In the present study, we pin down the origin of the coexistence of the large thermopower and the large conductivity in Na${}_x$CoO${}_2$. It is revealed that not just the density of states (DOS), the effective mass, nor the band width, but the peculiar {\it shape} of the $a_{1g}$ band referred to as the "pudding mold" type, which consists of a dispersive portion and a somewhat flat portion, is playing an important role in this phenomenon. The present study provides a new guiding principle for designing good thermoelectric materials.

5 pages

References in corpus (5)

• Fermi surface and quasiparticle dynamics of Na(x)CoO2 {x=0.7} investigated by Angle-Resolved Photoemission Spectroscopy
• ARPES on Na${}_{0.6}$CoO${}_2$: Fermi surface, extended flat dispersion, and unusual band splitting
• Precise Control of Band Filling in NaxCoO2
• Deformation of Electronic Structures Due to CoO6 Distortion and Phase Diagrams of NaxCoO2.yH2O
• Electronic theory for itinerant in-plane magnetic fluctuations in Na${}_x$CoO${}_2$

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