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Phonon lifetime in complex systems: Measurement and interpretation

19-20 déc. 2019
 - Lyon (France)

The workshop ""Phonon lifetime in complex systems: Measurement and interpretation"" will be organized in the Institue of Light and Matter" on December 19-20, 2019. The workshop focusses on the challenge of resolving and understanding acoustic phonon lifetimes in complex materials. It aims at gathering expertises in inelastic techniques (Neutrons, X-rays, pump-probe based techniques) and the theoretical approaches of phonon's anharmonicity. Crystal consists of a repeating 3D pattern of atoms, which behave like balls jointed by stiff springs. Quantized waves of motion of the atoms themselves, known as phonons, also flow through the crystal to carry heat. Phonons come in two types. Acoustic phonons act like sound waves, zipping through a crystal at a fixed speed regardless of their wavelength. They carry heat. In contrast, optical phonons generally have higher energies, move more slowly, and carry little heat. The two types of vibrations are very different: The simplest acoustic phonon consists of all the atoms sloshing back and forth in concert. The simplest optical phonon consists of neighboring atoms oscillating in opposite directions. Determining a phonon's individual properties, especially those of acoustic phonons, is then the basis of any knowledge-driven thermal engineering approach in energy-recovering and production strategies. While phonon energies can be relatively easily measured by inelastic scattering techniques (using X-rays or neutrons), this is not the case for the phonon's intrinsic energy width, whose detection in crystals still remains beyond the current resolution limits of state-of-the art spectrometers. However, it is fundamental to overcome such limitations for getting a microscopic understanding of thermal transport.
Discipline scientifique : Science des matériaux

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