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.

arXiv comment5 pages, 4 figures, accepted for publication in PRB

References in corpus (5)

• Spin entropy as the likely source of enhanced thermopower in $\rm\bf Na_xCo_2O_4
• 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
• Specific-heat evidence for strong electron correlations in the thermoelectric material (Na,Ca)Co_{2}O_{4}
• Electron-Hole Asymmetry in GdBaCo_{2}O_{5+x}: Evidence for Spin Blockade of Electron Transport in a Correlated Electron System
• Thermoelectric properties of the degenerate Hubbard model

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• Magneto-thermopower in the Weak Ferromagnetic Oxide CaRu0.8Sc0.2O3: An Experimental Test for the Kelvin Formula in a Magnetic Material
• An important role of temperature dependent scattering time in understanding the high temperature thermoelectric behavior of strongly correlated system: La${}_{0.75}$Ba${}_{0.25}$CoO${}_3$
• 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${}_{5+\delta }$ ($\delta \sim 0.65$)