Study of phonon anharmonicity in SrTiO3 published in Phys. Rev. Letters

April 9, 2020

Our paper on anharmonic phonons in the quantum paraelectric material SrTiO3 was published online in Physical Review Letters. Congrats to Xing!

Link to paper




Pronounced anomalies in the SrTiO3 dynamical structure factor, S(Q,E), including the disappearance of acoustic phonon branches at low temperatures, were uncovered with inelastic neutron scattering (INS) and simulations. The striking effect reflects anharmonic couplings between acoustic and optic phonons and the incipient ferroelectric instability near the quantum critical point. It is rationalized using a first-principles renormalized anharmonic phonon approach, pointing to nonlinear Ti-O hybridization causing unusual changes in real-space phonon eigenvectors, frequencies, group velocities, and scattering phase space. Our method is general and establishes how T dependences beyond the harmonic regime, assessed by INS mapping of large reciprocal-space volumes, provide real-space insights into anharmonic atomic dynamics near phase transitions.