From MHz to THz: How ultrasound and inelastic scattering see lattice dynamics

Abstract

Resonant ultrasound spectroscopy and direct phonon spectroscopy methods based on inelastic scattering of x-rays or neutrons provide complementary but also sometimes apparently contradicting pictures of the lattice dynamics. In order to resolve these apparent contradictions, the probe energy and length scales must be considered. I will review results for a few classes of energy material, such as bulk [Sergueev et al., Phys. Rev. B 91, 224304 (2015)] and nanostructured [Claudio et al. PCCP 16, 25701 (2014); pss B 251, 919 (2014); 213, 515 (2016); Klobes et al., Nanoscale 8, 856 (2016)] thermoelectric materials, magnetic and magnetocaloric materials [Herlitschke Phys. Rev. B 93, 094304 (2016); Klobes Phys. Rev. B 92, 014304 (2015)], or rutile oxides [Budai et al., in preparation]. [Work at Oak Ridge National Laboratory was supported by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division; work at Forschngszentrum Julich was supported by the Helm...