Abstract Details 113

Direct Structural Characterization of Photo-induced Coherent Phonon Oscillations in BaFe2As2
Abstract ID 113
Presenter Simon Gerber
Presentation Type Poster
Full Author List W.-S. Lee, Y. Zhang, M. Yi, P.S. Kirchmann, R.G. Moore, D. Zhu, G.L. Dakowski, O. Krupin, M. Chollet, J.J. Turner, J.-S. Lee, A. Mehta, H.-H. Kuo, I.R. Fisher, K.W. Kim, M. Wolf, Y.-D. Chuang, Z. Hussain, C.-C. Kao, T.P. Devereaux, and Z.-X. Shen

Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory


Insight into the relationship between the intertwined lattice, spin and orbital degrees of freedom is vital for the understanding of high-temperature superconductivity in iron-based materials. We address this question via ultrafast x-ray scattering to measure the time-evolution of a lattice Bragg peak in photo-excited BaFe2As2. Upon excitation with a femtosecond optical laser pulse, we observe an ultrafast increase and oscillation of the Bragg peak intensity with a frequency that is consistent with the coherent excitation of an A1g phonon mode. This mode modulates the Fe-As-Fe bond angle, which is crucial for determining the underlying electronic structure and also correlated with the superconducting transition temperature. We estimate the variation of the bond angle in this photo-induced coherent state by modeling the diffracted intensity of the Bragg peak in the presence of the A1g phonon mode. Our observations provide a direct view on the dynamics of the lattice degree of freedom that cannot be obtained by other means.



Funding Acknowledgement