Abstract
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.
| Original language | English |
|---|---|
| Article number | 145901 |
| Journal | Physical Review Letters |
| Volume | 124 |
| Issue number | 14 |
| DOIs | |
| State | Published - Apr 10 2020 |
Funding
We thank Olle Hellman for providing the TDEP software. We thank Andrei Savici and Melissa Graves-Brook for support and Jiawang Hong and Huibo Cao for helpful discussions. Neutron scattering measurements were supported by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division, under the Early Career Award No. DE-SC0016166. Data analysis and first-principles modeling were supported by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division, under Award No. DE-SC0019978. The research at Oak Ridge National Laboratory’s Spallation Neutron Source and High Flux Isotope Reactor was sponsored by the Scientific User Facilities Division, Office of Basic Energy Sciences, US DOE. Theoretical calculations were performed using resources of the National Energy Research Scientific Computing Center, A U.S. DOE Office of Science User Facility supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.