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