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Size effects on thermoelectricity in a strongly correlated oxide

TitleSize effects on thermoelectricity in a strongly correlated oxide
Publication TypeJournal Article
Year of Publication2012
AuthorsRavichandran, J., A. K. Yadav, W. Siemons, M. A. McGuire, V. Wu, A. Vailionis, A. Majumdar, and R. Ramesh
JournalPhysical Review B
Volume85
Issue8
Pagination085112
Date Published02/2012
Abstract

We investigated size effects on thermoelectricity in thin films of a strongly correlated layered cobaltate. At room temperature, the thermopower is independent of thickness down to 6 nm. This unusual behavior is inconsistent with the Fuchs-Sondheimer theory, which is used to describe conventional metals and semiconductors, and is attributed to the strong electron correlations in this material. On the other hand, the resistivity increases below a critical thickness of ∼30 nm, as expected. The temperature-dependent thermopower is similar for different thicknesses but the resistivity shows systematic changes with thickness. Our experiments highlight the differences in thermoelectric behavior of strongly correlated and uncorrelated systems when subjected to finite-size effects. We use the atomic-limit Hubbard model at the high-temperature limit to explain our observations. These findings provide new insights into decoupling electrical conductivity and thermopower in correlated systems.

URLhttp://link.aps.org/doi/10.1103/PhysRevB.85.085112
Short TitlePhys. Rev. B