Photoinduced insulator-to-metal transition and coherent acoustic phonon propagation in LaCoO3 thin films explored by femtosecond pump-probe ellipsometry
| Authors | |
|---|---|
| Year of publication | 2022 |
| Type | Article in Periodical |
| Magazine / Source | Physical Review B |
| MU Faculty or unit | |
| Citation | |
| Web | https://journals.aps.org/prb/abstract/10.1103/PhysRevB.105.235113 |
| Doi | http://dx.doi.org/10.1103/PhysRevB.105.235113 |
| Keywords | Carrier dynamics; Heat transfer; Lifetimes & widths; Metal-insulator transition; Optical conductivity |
| Description | We have studied ultrafast dynamics of thin films of LaCoO3 and La0.5Sr0.5CoO3 with femtosecond pumpprobe ellipsometry in the energy range of 1.6???3.4 eV. We have observed a large pump-induced transfer of spectral weight in LaCoO3 that corresponds to an insulator-to-metal transition. The photoinduced metallic state initially relaxes via a fast process with a decay constant of about 200 fs. Both LaCoO3 and La0.5Sr0.5CoO3 exhibit a significant secondary peak in the 1???30 ps range. Results of measurements on films with different thicknesses demonstrate that it corresponds to a propagation of an acoustic strain pulse. On timescales longer than 100 ps, heat diffusion to the substrate takes place that can be modeled with a biexponential decay. |
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