Wenjie Hao1,2,Minghui Gu1,3,Zhenyun Tian1,Shaohua Fu1,Meng Meng1,3,Hong Zhang2,Jiandong Guo1,3,Jimin Zhao1,3,4
Institute of Physics, Chinese Academy of Sciences1,Sichuan University2,School of Physical Sciences, University of Chinese Academy of Sciences3,Songshan Lake Materials Laboratory4
Wenjie Hao1,2,Minghui Gu1,3,Zhenyun Tian1,Shaohua Fu1,Meng Meng1,3,Hong Zhang2,Jiandong Guo1,3,Jimin Zhao1,3,4
Institute of Physics, Chinese Academy of Sciences1,Sichuan University2,School of Physical Sciences, University of Chinese Academy of Sciences3,Songshan Lake Materials Laboratory4
We employ ultrafast pump-probe spectroscopy to investigate the excited state photo-carrier dynamics in a tensile-strained thin film of LaCoO<sub>3</sub> on SrTiO<sub>3</sub> substrate. Through varying-fluence ultrafast relaxation dynamics, we obtain λ<Ω<sup>3</sup>> /<Ω> of LaCoO<sub>3</sub>/SrTiO<sub>3</sub> to be 294.9 ± 15.2 ps<sup>-2</sup> corresponding to a nominal electron phonon coupling constant value of <i>λ<sub>Eg</sub></i> = 0.97 ± 0.05. Furthermore, a fluence-dependent coherent acoustic phonon with a central frequency of 45.21 GHz is ultrafastly generated and detected. We attribute its origin to the ultrafast light pulse induced transient thermal strain.