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Title: Photoinduced coherent acoustic phonon dynamics inside Mott insulator Sr 2 IrO 4 films observed by femtosecond X-ray pulses

Abstract

We investigate the transient photoexcited lattice dynamics in a layered perovskite Mott insulator Sr2IrO4 film by femtosecond X-ray diffraction using a laser plasma-based X-ray source. The ultrafast structural dynamics of Sr2IrO4 thin films are determined by observing the shift and broadening of (0012) Bragg diffraction after excitation by 1.5 eV and 3.0 eV pump photons for films with different thicknesses. The observed transient lattice response can be well interpreted as a distinct three-step dynamics due to the propagation of coherent acoustic phonons generated by photoinduced quasiparticles (QPs). Employing a normalized phonon propagation model, we found that the photoinduced angular shifts of the Bragg peak collapse into a universal curve after introducing normalizedn coordinates to account for different thicknesses and pump photon energies, pinpointing the origin of the lattice distortion and its early evolution. In addition, a transient photocurrent measurement indicates that the photoinduced QPs are charge neutral excitons. Mapping the phonon propagation and correlating its dynamics with the QP by ultrafast X-ray diffraction (UXRD) establish a powerful way to study electron-phonon coupling and uncover the exotic physics in strongly correlated systems under nonequilibrium conditions.

Authors:
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Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
University of Tennessee - Dept. of Physics and Astronomy; Chinese Academy of Sciences - Institute of High Energy Physics (IHEP); National Natural Science Foundation of China (NNSFC); USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1360146
DOE Contract Number:  
AC02-06CH11357
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 110; Journal Issue: 15
Country of Publication:
United States
Language:
English

Citation Formats

Zhang, Bing-Bing, Liu, Jian, Wei, Xu, Sun, Da-Rui, Jia, Quan-Jie, Li, Yuelin, and Tao, Ye. Photoinduced coherent acoustic phonon dynamics inside Mott insulator Sr 2 IrO 4 films observed by femtosecond X-ray pulses. United States: N. p., 2017. Web. doi:10.1063/1.4980062.
Zhang, Bing-Bing, Liu, Jian, Wei, Xu, Sun, Da-Rui, Jia, Quan-Jie, Li, Yuelin, & Tao, Ye. Photoinduced coherent acoustic phonon dynamics inside Mott insulator Sr 2 IrO 4 films observed by femtosecond X-ray pulses. United States. doi:10.1063/1.4980062.
Zhang, Bing-Bing, Liu, Jian, Wei, Xu, Sun, Da-Rui, Jia, Quan-Jie, Li, Yuelin, and Tao, Ye. Mon . "Photoinduced coherent acoustic phonon dynamics inside Mott insulator Sr 2 IrO 4 films observed by femtosecond X-ray pulses". United States. doi:10.1063/1.4980062.
@article{osti_1360146,
title = {Photoinduced coherent acoustic phonon dynamics inside Mott insulator Sr 2 IrO 4 films observed by femtosecond X-ray pulses},
author = {Zhang, Bing-Bing and Liu, Jian and Wei, Xu and Sun, Da-Rui and Jia, Quan-Jie and Li, Yuelin and Tao, Ye},
abstractNote = {We investigate the transient photoexcited lattice dynamics in a layered perovskite Mott insulator Sr2IrO4 film by femtosecond X-ray diffraction using a laser plasma-based X-ray source. The ultrafast structural dynamics of Sr2IrO4 thin films are determined by observing the shift and broadening of (0012) Bragg diffraction after excitation by 1.5 eV and 3.0 eV pump photons for films with different thicknesses. The observed transient lattice response can be well interpreted as a distinct three-step dynamics due to the propagation of coherent acoustic phonons generated by photoinduced quasiparticles (QPs). Employing a normalized phonon propagation model, we found that the photoinduced angular shifts of the Bragg peak collapse into a universal curve after introducing normalizedn coordinates to account for different thicknesses and pump photon energies, pinpointing the origin of the lattice distortion and its early evolution. In addition, a transient photocurrent measurement indicates that the photoinduced QPs are charge neutral excitons. Mapping the phonon propagation and correlating its dynamics with the QP by ultrafast X-ray diffraction (UXRD) establish a powerful way to study electron-phonon coupling and uncover the exotic physics in strongly correlated systems under nonequilibrium conditions.},
doi = {10.1063/1.4980062},
journal = {Applied Physics Letters},
number = 15,
volume = 110,
place = {United States},
year = {Mon Apr 10 00:00:00 EDT 2017},
month = {Mon Apr 10 00:00:00 EDT 2017}
}