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Gigahertz longitudinal acoustic phonons originating from ultrafast ligand field transitions in hematite thin films

Journal Article


Abstract


  • The creation and propagation of longitudinal acoustic phonons (LAPs) in high quality hematite thin films (α-Fe2O3) epitaxially grown on different substrates (BaTiO3, SrTiO3, and LaAlO3) are investigated using the femtosecond pump–probe technique. Transient reflection measurements (ΔR/R) indicate the photo-excited electron dynamics, and 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. LAPs in α-Fe2O3 film can be 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 modulations of the sound velocity and the out-of-plane elastic properties are demonstrated in α-Fe2O3 film on different substrates.

UOW Authors


  •   Xu, Yue (external author)
  •   Jin, Zuanming (external author)
  •   Zhang, Zhengbing (external author)
  •   Zhang, Zeyu (external author)
  •   Lin, Xian (external author)
  •   Ma, Guohong (external author)
  •   Cheng, Zhenxiang

Publication Date


  • 2014

Citation


  • Xu, Y., Jin, Z., Zhang, Z., Zhang, Z., Lin, X., Ma, G. & Cheng, Z. (2014). Gigahertz longitudinal acoustic phonons originating from ultrafast ligand field transitions in hematite thin films. Chinese Physics B, 23 (4), 044206-1-044206-4.

Scopus Eid


  • 2-s2.0-84899535819

Ro Metadata Url


  • http://ro.uow.edu.au/aiimpapers/1073

Start Page


  • 044206-1

End Page


  • 044206-4

Volume


  • 23

Issue


  • 4

Abstract


  • The creation and propagation of longitudinal acoustic phonons (LAPs) in high quality hematite thin films (α-Fe2O3) epitaxially grown on different substrates (BaTiO3, SrTiO3, and LaAlO3) are investigated using the femtosecond pump–probe technique. Transient reflection measurements (ΔR/R) indicate the photo-excited electron dynamics, and 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. LAPs in α-Fe2O3 film can be 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 modulations of the sound velocity and the out-of-plane elastic properties are demonstrated in α-Fe2O3 film on different substrates.

UOW Authors


  •   Xu, Yue (external author)
  •   Jin, Zuanming (external author)
  •   Zhang, Zhengbing (external author)
  •   Zhang, Zeyu (external author)
  •   Lin, Xian (external author)
  •   Ma, Guohong (external author)
  •   Cheng, Zhenxiang

Publication Date


  • 2014

Citation


  • Xu, Y., Jin, Z., Zhang, Z., Zhang, Z., Lin, X., Ma, G. & Cheng, Z. (2014). Gigahertz longitudinal acoustic phonons originating from ultrafast ligand field transitions in hematite thin films. Chinese Physics B, 23 (4), 044206-1-044206-4.

Scopus Eid


  • 2-s2.0-84899535819

Ro Metadata Url


  • http://ro.uow.edu.au/aiimpapers/1073

Start Page


  • 044206-1

End Page


  • 044206-4

Volume


  • 23

Issue


  • 4