@article{4231f88360ef4a87b3a440b62f835483,
title = "Crossover from incoherent to coherent phonon scattering in epitaxial oxide superlattices",
abstract = "Elementary particles such as electrons or photons are frequent subjects of wave-nature-driven investigations, unlike collective excitations such as phonons. The demonstration of wave-particle crossover, in terms of macroscopic properties, is crucial to the understanding and application of the wave behaviour of matter. We present an unambiguous demonstration of the theoretically predicted crossover from diffuse (particle-like) to specular (wave-like) phonon scattering in epitaxial oxide superlattices, manifested by a minimum in lattice thermal conductivity as a function of interface density. We do so by synthesizing superlattices of electrically insulating perovskite oxides and systematically varying the interface density, with unit-cell precision, using two different epitaxial-growth techniques. These observations open up opportunities for studies on the wave nature of phonons, particularly phonon interference effects, using oxide superlattices as model systems, with extensive applications in thermoelectrics and thermal management.",
author = "Jayakanth Ravichandran and Yadav, {Ajay K.} and Ramez Cheaito and Rossen, {Pim B.} and Arsen Soukiassian and Suresha, {S. J.} and Duda, {John C.} and Foley, {Brian M.} and Lee, {Che Hui} and Ye Zhu and Lichtenberger, {Arthur W.} and Moore, {Joel E.} and Muller, {David A.} and Schlom, {Darrell G.} and Hopkins, {Patrick E.} and Arun Majumdar and Ramamoorthy Ramesh and Zurbuchen, {Mark A.}",
note = "Funding Information: The work on SrTiO3/CaTiO3 superlattices was supported by the US Department of Energy, Office of Basic Energy Sciences under Contract No. DE-AC02-05CH11231. The work on SrTiO3/BaTiO3 superlattices by A.S., C-H.L., D.G.S. and M.A.Z. was supported by the Defense Advanced Research Projects Agency (DARPA) and the US Army Aviation and Missile Research, Development, and Engineering Center (AMRDEC) through Grant No. W31P4Q-09-1-0005. TEM sample preparation for some of the SrTiO3/BaTiO3 superlattices was performed by the UCLA Nanoelectronics Research Facility. We acknowledge the use of instruments at the Electron Imaging Center for NanoMachines (EICN) supported by NIH (1S10RR23057 to Z.H.Z.) at the California NanoSystems Institute (CNSI), UCLA. Electron microscopy and spectroscopy of SrTiO3/BaTiO3 at Cornell by Y.Z. and D.A.M. was supported by the Army Research Office (ARO) grant W911NF-09-1-0415 and the electron microscopy facility of the Cornell Center for Materials Research (CCMR) by the National Science Foundation Materials Research Science and Engineering Centers (MRSEC) programme (DMR 1120296). P.E.H. is grateful for financial support from Army Research office (ARO) grant W911NF-13-1-0378. TDTR measurements on the SrTiO3/CaTiO3 superlattices at the University of Virginia were supported by the National Science Foundation (NSF) grant CBET-1339436. J.R. acknowledges the fellowship from Link Foundation. The authors wish to express deep gratitude to D. G. Cahill for measuring the thermal conductivity of a significant number of the samples by TDTR, and for many thoughtful discussions. The authors also wish to acknowledge the contributions of CrysTec GmbH for providing the high-quality single-crystal substrates that were used in this study.",
year = "2014",
month = feb,
doi = "10.1038/nmat3826",
language = "English (US)",
volume = "13",
pages = "168--172",
journal = "Nature Materials",
issn = "1476-1122",
publisher = "Nature Publishing Group",
number = "2",
}