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Gigahertz longitudinal acoustic phonons originated from ultrafast ligand field transitions in hematite thin films |
| Yue Xu |
| 上海大学理学院物理系 |
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Abstract The creation and propagation of longitudinal acoustic phonons (LAP) in high quality hematite thin films (α-Fe2O3) epitaxially grown on different substrates (BaTiO3, SrTiO3, and LaAlO3) are investigated using femtosecond pump-probe technique. Transient reflection measurements (ΔR/R) indicate the photoexcited electron dynamics, the initial decay less than 1 ps and the slow decay of ~500 ps are attributed to the electron-LO phonon coupling and electron-hole nonradiative recombination, respectively. LAP in α-Fe2O3 film can created by ultrafast excitation of the ligand field state, such as the ligand field transitions under 800 nm-excitation as well as the ligand to metal charge-transfer with 400 nm-excitation. The strain modulation of sound velocity and out-of-plane elastic properties are demonstrated in α-Fe2O3 film on different substrates.
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Received: 13 June 2013
Published: 31 October 2013
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Corresponding Authors:
Yue Xu
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Cite this article:
Yue Xu Gigahertz longitudinal acoustic phonons originated from ultrafast ligand field transitions in hematite thin films Chin. Phys. B 0
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