| Autor: |
Porer, M., Fechner, M., Bothschafter, E., Rettig, L., Savoini, M., Esposito, V., Rittmann, J., Kubli, M., Neugebauer, M. J., Abreu, E., Kubacka, T., Huber, T., Lantz, G., Parchenko, S., Grübel, S., Paarmann, A., Noack, J., Beaud, P., Ingold, G., Aschauer, U., Johnson, S. L., Staub, U. |
| Rok vydání: |
2018 |
| Předmět: |
|
| Zdroj: |
Phys. Rev. Lett. 121, 055701 (2018) |
| Druh dokumentu: |
Working Paper |
| DOI: |
10.1103/PhysRevLett.121.055701 |
| Popis: |
The ultrafast dynamics of the octahedral rotation in Ca:SrTiO3 is studied by time resolved x-ray diffraction after photo excitation over the band gap. By monitoring the diffraction intensity of a superlattice reflection that is directly related to the structural order parameter of the soft-mode driven antiferrodistortive phase in Ca:SrTiO3, we observe a ultrafast relaxation on a 0.2 ps timescale of the rotation of the oxygen octahedron, which is found to be independent of the initial temperaure despite large changes in the corresponding soft-mode frequency. A further, much smaller reduction on a slower picosecond timescale is attributed to thermal effects. Time-dependent density-functional-theory calculations show that the fast response can be ascribed to an ultrafast displacive modification of the soft-mode potential towards the normal state, induced by holes created in the oxygen 2p states. |
| Databáze: |
arXiv |
| Externí odkaz: |
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