Anomalous Thermoelectric Response in an Orbital-Ordered Oxide Near and Far from Equilibrium

Abstract

We report the thermoelectric transport properties in the orbital-ordered Mott insulating phase of Ca${}_2$RuO${}_4$ close to and far from equilibrium. Near equilibrium conditions where the temperature gradient is only applied to the sample, an insulating but non-monotonic temperature variation of the Seebeck coefficient is observed, which is accounted for in terms of a temperature-induced suppression of the orbital order. In non-equilibrium conditions where we have applied high electrical currents, we find that the Seebeck coefficient is anomalously increased in magnitude with increasing external current. The present result clearly demonstrates a non-thermal effect since the heating simply causes a decrease of the Seebeck coefficient, implying a non-trivial non-equilibrium effect such as a modification of the spin and orbital state in currents.

5 pages, 3 figures, Selected as Editors' Choice

References in corpus (1)

• On the thermoelectricity of correlated electrons in the zero-temperature limit

Cited by in corpus (4)

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• Correlation in transport coefficients of hole-doped CuRhO${}_2$ single crystals
• Anomalous scaling law for thermoelectric transport of 2D-confined electrons in an organic molecular system
• Thermoelectric transport properties of the quasi-one-dimensional dimer-Mott insulator ${\beta }^{\prime }$-(BEDT-TTF)${}_2$ICl${}_2$