2016/10/31 by Jiecheng Zhang, J. -C. Zhang, E. M. Levenson-Falk +9
Physics and Astronomy · #Advanced Condensed Matter Physics #Condensed matter physics #Cuprate #Materials science #Phonon #Physics #Physics of Superconductivity and Magnetism #Quantum and electron transport phenomena #Quasiparticle #Superconductivity #Thermal diffusivity #Thermodynamics #cond-mat.supr-con #hep-th
paper · pdf · doi:10.1073/pnas.1703416114
8 pages + 4 pages supporting information
openalex publication_date 2017/05/08 · arxiv created 2017/05/15 · arxiv updated 2017/06/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
The thermal diffusivity in the [Formula: see text] plane of underdoped YBCO crystals is measured by means of a local optical technique in the temperature range of 25-300 K. The phase delay between a point heat source and a set of detection points around it allows for high-resolution measurement of the thermal diffusivity and its in-plane anisotropy. Although the magnitude of the diffusivity may suggest that it originates from phonons, its anisotropy is comparable with reported values of the electrical resistivity anisotropy. Furthermore, the anisotropy drops sharply below the charge order transition, again similar to the electrical resistivity anisotropy. Both of these observations suggest that the thermal diffusivity has pronounced electronic as well as phononic character. At the same time, the small electrical and thermal conductivities at high temperatures imply that neither well-defined electron nor phonon quasiparticles are present in this material. We interpret our results through a strongly interacting incoherent electron-phonon "soup" picture characterized by a diffusion constant [Formula: see text], where [Formula: see text] is the soup velocity, and scattering of both electrons and phonons saturates a quantum thermal relaxation time [Formula: see text].