Origin of the large thermoelectric power in oxygen-variable RBaCo_{2}O_{5+x} (R=Gd, Nd)

Abstract

Thermoelectric properties of GdBaCo_{2}O_{5+x} and NdBaCo_{2}O_{5+x} single crystals have been studied upon continuous doping of CoO_2 planes with either electrons or holes. The thermoelectric response and the resistivity behavior reveal a hopping character of the transport in both compounds, providing the basis for understanding the recently found remarkable divergence of the Seebeck coefficient at x=0.5. The doping dependence of the thermoelectric power evinces that the configurational entropy of charge carriers, enhanced by their spin and orbital degeneracy, plays a key role in the origin of the large thermoelectric response in these correlated oxides.

5 pages, 4 figures, accepted for publication in PRB

References in corpus (1)

• Transport and magnetic properties of GdBaCo_{2}O_{5+x} single crystals: A cobalt oxide with square-lattice CoO_2 planes over a wide range of electron and hole doping

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• Prominent electron-hole asymmetry in thermoelectric transport of LaCoO${}_3$
• Proof-of-concept thermoelectric oxygen sensor exploiting oxygen mobility of GdBaCo2O5+δ
• Carrier filtering effect for enhanced thermopower in a body-centered tetragonal ruthenate
• Coupling of magnetism and transport properties to the lattice degrees of freedom in NdBaCo${}_2$O${}_{5+\delta }$ ($\delta \sim 0.65$)