Phonon transport in perovskite SrTiO₃from first principles

Abstract

We investigate phonon transport in perovskite strontium titanate (SrTiO3), which is stable above its phase transition temperature (∼105 K), by using first-principles molecular dynamics and anharmonic lattice dynamics. Unlike conventional ground-state-based perturbation methods that give imaginary phonon frequencies, the current calculation reproduces stable phonon dispersion relations observed in experiments. We find that the contribution of optical phonons to the overall lattice thermal conductivity is larger than 60%, which is markedly different from the usual picture with the dominant contribution from acoustic phonons. Mode-dependent and pseudopotential-dependent analyses suggest the strong attenuation of acoustic phonon transport originating from strong anharmonic coupling with the transversely polarized ferroelectric modes.