title: Localization of propagative phonons in a perfectly crystalline solid.
abstract: Perfectly crystalline solids are excellent heat conductors. Prominent counterexamples are intermetallic clathrates, guest-host systems with a high potential for thermoelectric applications due to their ultralow thermal conductivities. Our combined experimental and theoretical investigation of the lattice dynamics of a particularly simple binary representative, Ba(8)Si(46), identifies the mechanism responsible for the reduction of lattice thermal conductivity intrinsic to the perfect crystal structure. Above a critical wave vector, the purely harmonic guest-host interaction leads to a drastic transfer of spectral weight to the guest atoms, corresponding to a localization of the propagative phonons.
authors: Institute of Light and Matter, UMR5306 Université Lyon 1-CNRS, Université de Lyon 69622 Villeurbanne cedex, France.
authors: S
authors: S
authors: Pailhès
authors: Institut für Theoretische und Angwandte Physik, Universität Stuttgart, D-70550 Stuttgart, Germany and Institute of Materials Science and Technology, Vienna University of Technology, A-1040 Vienna, Austria.
authors: H
authors: H
authors: Euchner
authors: Institute of Light and Matter, UMR5306 Université Lyon 1-CNRS, Université de Lyon 69622 Villeurbanne cedex, France and CNRS, SIMAP, F-38000 Grenoble, France.
authors: V M
authors: VM
authors: Giordano
authors: Institute of Light and Matter, UMR5306 Université Lyon 1-CNRS, Université de Lyon 69622 Villeurbanne cedex, France.
authors: R
authors: R
authors: Debord
authors: Université de Lyon, INSA-Lyon, CETHIL UMR5008, F-69621 Villeurbanne, France.
authors: A
authors: A
authors: Assy
authors: Université de Lyon, CNRS, CETHIL UMR5008, F-69621, France.
authors: S
authors: S
authors: Gomès
authors: European Synchrotron Radiation Facility, BP 220, F-38043 Grenoble cedex, France.
authors: A
authors: A
authors: Bosak
authors: Institute of Light and Matter, UMR5306 Université Lyon 1-CNRS, Université de Lyon 69622 Villeurbanne cedex, France.
authors: D
authors: D
authors: Machon
authors: Institute of Solid State Physics, Vienna University of Technology, 1040 Vienna, Austria.
authors: S
authors: S
authors: Paschen
authors: Université Grenoble Alpes, SIMAP, F-38000 Grenoble, France and CNRS, SIMAP, F-38000 Grenoble, France.
authors: M
authors: M
authors: de Boissieu