Photoinduced insulator-to-metal transition and coherent acoustic phonon propagation in LaCoO.sub.3./sub. thin films explored by femtosecond pump-probe ellipsometry

0560857 - FZÚ 2023 RIV US eng J - Journal Article
Zahradník, Martin - Kiaba, M. - Espinoza Herrera, Shirly J. - Rebarz, Mateusz - Andreasson, Jakob - Caha, O. - Abadizaman, F. - Munzar, D. - Dubroka, A.
Photoinduced insulator-to-metal transition and coherent acoustic phonon propagation in LaCoO₃ thin films explored by femtosecond pump-probe ellipsometry.
Physical Review B. Roč. 105, č. 23 (2022), č. článku 235113. ISSN 2469-9950. E-ISSN 2469-9969
R&D Projects: GA MŠMT LM2018110; GA MŠMT EF15_003/0000447; GA MŠMT EF16_019/0000789; GA MŠMT LM2017094
Grant - others:OP VVV - ELIBIO(XE) CZ.02.1.01/0.0/0.0/15_003/0000447; OP VVV - ADONIS(XE) CZ.02.1.01/0.0/0.0/16_019/0000789
Institutional support: RVO:68378271
Keywords : femtosecond pump-probe ellipsometry * LaCoO3 thin films * acustic strain pulse
OECD category: Particles and field physics
Impact factor: 3.7, year: 2022
Method of publishing: Open access

We have studied ultrafast dynamics of thin films of LaCoO 3 and La 0.5 Sr 0.5 CoO 3 with femtosecond pump-probe ellipsometry in the energy range of 1.6–3.4 eV. We have observed a large pump-induced transfer of spectral weight in LaCoO 3 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 LaCoO 3 and La 0.5 Sr 0.5 CoO 3 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.
Permanent Link: https://hdl.handle.net/11104/0333641