Abstract
We use an x-ray free-electron laser to study the lattice dynamics following photoexcitation with ultrafast near-UV light (wavelength 266 nm, 50 fs pulse duration) of the incipient ferroelectric potassium tantalate, KTaO3. By probing the lattice dynamics corresponding to multiple Brillouin zones through the x-ray diffuse scattering with pulses from the Linac Coherent Light Source (LCLS) (wavelength 1.3 Å and <10 fs pulse duration), we observe changes in the diffuse intensity associated with a hardening of the transverse acoustic phonon branches along Γ to X and Γ to M. Using force constants from density functional theory, we fit the quasiequilibrium intensity and obtain the instantaneous lattice temperature and density of photoexcited charge carriers. The density functional theory calculations demonstrate that photoexcitation transfers charge from oxygen 2p derived π-bonding orbitals to Ta 5d derived antibonding orbitals, further suppressing the ferroelectric instability and increasing the stability of the cubic, paraelectric structure.
| Original language | English (US) |
|---|---|
| Article number | 127601 |
| Journal | Physical review letters |
| Volume | 129 |
| Issue number | 12 |
| DOIs | |
| State | Published - Sep 16 2022 |
Funding
The experimental work was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences through the Division of Materials Sciences and Engineering through FWP No. 2018LANLBES16 (M.-C. L. and R. P. P.), Contract No. DE-AC02-76SF00515 (S. W. T., V. K., Y. H., G. dP., M. T., and D. A. R.), and Contract No. DE-SC0019126 (A. A. M. and K. A. N.). Use of the L. C. L. S. was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Contract No. DE-AC02-76SF00515. Work at Northwestern University was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Award No. DE-SC-0012375. N. S. gratefully acknowledges the support of the U.S. Department of Energy through the Los Alamos National Laboratory LDRD program. The computational work used resources of the National Energy Research Scientific Computing Center (NERSC), a U.S. DOE Office of Science User Facility located at Lawrence Berkeley National Laboratory, operated under Contract No. DE-AC02-05CH11231, and at the Center for Nanoscale Materials, an Office of Science user facility, supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
ASJC Scopus subject areas
- General Physics and Astronomy