Direct manipulation of the atomic lattice using intense long-wavelength laser pulses has become a viable approach to create new states of matter in complex materials. Conventionally, a high-frequency vibrational mode is driven resonantly by a mid-infrared laser pulse and the lattice structure is modified through indirect coupling of this infrared-active phonon to other, lower-frequency lattice modulations. Here, we drive the lowest-frequency optical phonon in the prototypical transition metal oxide SrTiO 3 well into the anharmonic regime with an intense terahertz field. We show that it is possible to transfer energy to higher-frequency phonon modes through nonlinear coupling. Our observations are carried out by directly mapping the lattice response to the coherent drive field with femtosecond X-ray pulses, enabling direct visualization of the atomic displacements.
|Data di pubblicazione:||2019|
|Titolo:||Terahertz-driven phonon upconversion in SrTiO 3|
|Digital Object Identifier (DOI):||http://dx.doi.org/10.1038/s41567-018-0408-1|
|Appare nelle tipologie:||2.1 Articolo su rivista |
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|s41567-018-0408-1.pdf||Versione dell'editore||Accesso chiuso-personale||Riservato|