Heterostructures composed of transition metal oxides with strong electron correlation offer a unique opportunity to design new artificial materials whose electrical, magnetic and optical properties can be manipulated by tailoring the occupation of the 3d-orbitals of the transition metal in the compound. This possibility is an implication of symmetry constraints at interfaces resulting in a delicate interplay of spin-, charge-, orbital and lattice interactions of electrons. In turn, the material properties are sensitive to external perturbations such as strain, electrical and magnetic fields and photon flux as well. In this contribution we use photon flux exposure to explore the consequences of superlattice formation of YBa₂Cu₃O_7–δ/La 2_/3Ca_1/3MnO₃ on the entropy transport, especially on the Seebeck coefficient. In addition to the investigation of the fundamental aspects of entropy transport in oxide superlattices, the driving force for this work is the development of optical sensing devices. The method applied is based on the off-diagonal thermoelectric effect (ODTE) appearing in films deposited on substrates with a vicinal cut. This well-known principle serves as a technique to investigate the anisotropic transport properties and the components of the Seebeck tensor in these superlattices. It could be shown that the normalized ODTE signals scale linearly with the number of interfaces in the structures. We observed an enhancement of the ODTE signals by a factor of four due to superlattice formation. The results are discussed with respect to cross-plane coherent backscattering of phonon waves at the superlattice interfaces and the thermal boundary resistance at the YBa₂Cu₃O_7–δ/La_2/3Ca_1/3MnO₃ interfaces.

Date Published: 8 March 2014
PDF: 11 pages
Proc. SPIE 8987, Oxide-based Materials and Devices V, 898713 (8 March 2014); doi: 10.1117/12.2047336

Published in SPIE Proceedings Vol. 8987:
Oxide-based Materials and Devices V
Ferechteh H. Teherani; David C. Look; David J. Rogers, Editor(s)