Unlike many superlattice structures, Ruddlesden-Popper phases have atomically abrupt interfaces useful for interrogating how periodic atomic layers affect thermal properties. Here, we measure the thermal conductivity in thin films of the n = 1-5 and 10 members of the (SrTiO3)nSrO Ruddlesden-Popper superlattices grown by molecular-beam epitaxy and compare the results to a single crystal of the n = 1 Ruddlesden-Popper SrLaAlO4. The thermal conductivity cross-plane to the superlattice layering (k33) is measured using time-domain thermoreflectance as a function of temperature and the results are compared to first-principles calculations. The thermal conductivity of this homologous series decreases with increasing interface density. Characterization by x-ray diffraction and scanning transmission electron microscopy confirms that these samples have a Ruddlesden-Popper superlattice structure.
N. M. Dawley and E. K. Pek and C. H. Lee and E. J. Ragasa and X. Xiong and K. Lee and S. R. Phillpot and A. V. Chernatynskiy and D. G. Cahill and D. G. Schlom, "Thermal Conductivity of the n = 1-5 and 10 Members of the (SrTiO₃)ₙSrO Ruddlesden-Popper Superlattices," Applied Physics Letters (AIP), vol. 118, no. 9, American Institute of Physics (AIP), Mar 2021.
The definitive version is available at https://doi.org/10.1063/5.0037765
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04 Mar 2021