Moving atoms with enhanced THz pulses and tracking them with ultrashort x-ray pulses on an XFEL

Left: Calculated electric field enhancement of the metallic slit structure on a StrTiO3 film grown on LSAT. Center: Time dependence of various diffraction peaks during THz excitation showing the response of the atomic motions induced by the electric field. Right: Time dependence for various electric field strengths in the THz pulse, and showing a linear dependence of the atomic motions versus field strength (inset).
Left: Calculated electric field enhancement of the metallic slit structure on a StrTiO3 film grown on LSAT. Center: Time dependence of various diffraction peaks during THz excitation showing the response of the atomic motions induced by the electric field. Right: Time dependence for various electric field strengths in the THz pulse, and showing a linear dependence of the atomic motions versus field strength (inset).

Metallic field enhancement structures have been used to enhance the electric field of single cycle THz pulses acting on a SrTiO3 perovskite film. The enhanced electric field results in enhanced motion of atoms that has been tracked by ultrashort pulses from the x-ray free electron Laser LCLS at SLAC. The results show that we can obtained enhancements of a factor of five in the corresponding polar distortion induced in centrosymmetric SrTiO3 and are able to track the atomic motions as a function of electric field within the THz pulse. Being able to excite directly a polar phonon mode with strong electric fields and studying the corresponding motions on a XFEL has strong potential for the study of non-linear couplings between phonons and electronic structure. It is particularly important and interesting to be able to follow directly the atomic motions during the temporal electric field variations within the excitation on ultrafast timescales.

Original publication
Local Terahertz Field Enhancement for Time-Resolved X-ray Diffraction
M. Kozina, M. Pancald, C. Bernhard, T. van Driel, J.M. Glownia, P. Marsik, M. Radovic, C.A.F. Vaz, D. Zhu, S. Bonetti, U. Staub, and M.C. Hoffmann
Appl. Phys. Lett. 110, 081106 (2017)
DOI: 10.1063/1.4977088
PSI Contact
Urs Staub
Laboratory for Synchrotron Radiation — Condensed Matter Physics
Swiss Light Source, Paul Scherrer Institute
5232 Villigen PSI, Switzerland
Phone: +41 56 310 4494, e-mail: urs.staub@psi.ch
SLAC Contact
Matthias Hoffmann
Linac Coherent Light Source
SLAC National Accelerator Laboratory
Menlo Park, California 94025, USA
Phone: +1 650 926-2521, e-mail: hoffmann@SLAC.Stanford.EDU