RESUMEN
Motivated by recent experimental findings, we study the contribution of a quantum critical optical phonon branch to the thermal conductivity of a paraelectric system. We consider the proximity of the optical phonon branch to transverse acoustic phonon branch and calculate its contribution to the thermal conductivity within the Kubo formalism. We find a low temperature power law dependence of the thermal conductivity asTα, with 1 <α< 2, (lower thanT3behavior) due to optical phonons near the quantum critical point. This result is in accord with the experimental findings and indicates the importance of quantum fluctuations in the thermal conduction in these materials.
RESUMEN
The temperature dependence of the static dielectric susceptibility of a system with strongly coupled fluctuating dipoles is calculated within a self-consistent mean fluctuation field approximation. Results are qualitatively in good agreement with a quantum paraelectric SrTiO(3) in the low temperature regime. We identify this system as a gapped quantum paraelectric and suggest a possible experimental realization of a quantum critical paraelectric through the application of hydrostatic pressure or doping by impurity.
