Browsing by Author "Chuang, W. T."

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Pressure-dependent electronic structures in multiferroic DyMnO(3): A combined lifetime-broadening-suppressed x-ray absorption spectroscopy and ab initio electronic structure study
(2010-10-21)
Chen, J. M.
;
Lee, J. M.
;
Chou, T. L.
;
Chen, S. A.
;
Huang, S. W.
Variations in the electronic structure and structural distortion in multiferroic DyMnO(3) were probed by synchrotron x-ray diffraction, lifetime-broadening-suppressed x-ray absorption spectroscopy (XAS), and ab initio electronic structure calculations. The refined x-ray diffraction data enabled an observation of a diminished local Jahn-Teller distortion of Mn sites within MnO(6) octahedra in DyMnO(3) on applying the hydrostatic pressure. The intensity of the white line in Mn K-edge x-ray absorption spectra of DyMnO(3) progressively increased with the increasing pressure. With the increasing hydrostatic pressure, the absorption threshold of an Mn K-edge spectra of DyMnO(3) shifted toward a greater energy, whereas the pre-edge line slightly shifted to a smaller energy. We provide the spectral evidence for the pressure-induced bandwidth broadening for manganites. The intensity enhancement of the white line in Mn K-edge spectra is attributed to a diminished Jahn-Teller distortion of MnO(6) octahedra in compressed DyMnO(3). A comparison of the pressure-dependent XAS spectra with the ab initio electronic structure calculations and full calculations of multiple scattering using the code FDMNES shows the satisfactory agreement between experimental and calculated Mn K-edge spectra. (C) 2010 American Institute of Physics. [doi:10.1063/1.3490400]
Pressure-dependent electronic structures in multiferroic DyMnO3: A combined lifetime-broadening-suppressed x-ray absorption spectroscopy and ab initio electronic structure study
(2010-10-21)
Chen, J. M.
;
Lee, J. M.
;
Chou, T. L.
;
Chen, S. A.
;
Huang, S. W.
Variations in the electronic structure and structural distortion in multiferroic DyMnO3 were probed by synchrotron x-ray diffraction, lifetime-broadening-suppressed x-ray absorption spectroscopy (XAS), and ab initio electronic structure calculations. The refined x-ray diffraction data enabled an observation of a diminished local Jahn-Teller distortion of Mn sites within MnO6 octahedra in DyMnO3 on applying the hydrostatic pressure. The intensity of the white line in Mn K-edge x-ray absorption spectra of DyMnO3 progressively increased with the increasing pressure. With the increasing hydrostatic pressure, the absorption threshold of an Mn K-edge spectra of DyMnO3 shifted toward a greater energy, whereas the pre-edge line slightly shifted to a smaller energy. We provide the spectral evidence for the pressure-induced bandwidth broadening for manganites. The intensity enhancement of the white line in Mn K-edge spectra is attributed to a diminished Jahn-Teller distortion of MnO6 octahedra in compressed DyMnO3. A comparison of the pressure-dependent XAS spectra with the ab initio electronic structure calculations and full calculations of multiple scattering using the code FDMNES shows the satisfactory agreement between experimental and calculated Mn K-edge spectra. (C) 2010 American Institute of Physics. [doi:10.1063/1.3490400]
Pressure-induced structural distortion of TbMnO(3): A combined x-ray diffraction and x-ray absorption spectroscopy study
(2009-04-01)
Chen, J. M.
;
Chou, T. L.
;
Lee, J. M.
;
Chen, S. A.
;
Chan, T. S.
The variation of electronic states and structural distortion in highly compressed multiferroic TbMnO(3) was probed by x-ray diffraction (XRD) and x-ray absorption spectroscopy (XAS) using synchrotron radiation. Refined XRD data enabled observation of a reduced local Jahn-Teller (JT) distortion of Mn sites within MnO(6) octahedra in TbMnO(3) with increasing hydrostatic pressure. A progressively increasing intensity of the white line in Mn K-edge x-ray absorption spectra of TbMnO(3) was detected with increasing pressure. The absorption threshold of Mn K-edge spectra of TbMnO(3) is shifted toward higher energy, whereas the pre-edge peak is slightly shifted to lower energy with increasing hydrostatic pressure. We provide spectral evidence for pressure-induced bandwidth broadening for mangnites. The enhanced intensity of the white line and the shifted absorption threshold of Mn K-edge spectra are explained in terms of a reduced JT distortion of MnO(6) octahedra in compressed TbMnO(3). Comparison of XAS data with full-multiple-scattering calculations using code FDMNES shows satisfactory agreement between experimental and calculated Mn K-edge spectra.
Pressure-induced structural distortion of TbMnO3: A combined x-ray diffraction and x-ray absorption spectroscopy study
(2009-04-01)
Chen, J. M.
;
Chou, T. L.
;
Lee, J. M.
;
Chen, S. A.
;
Chan, T. S.
The variation of electronic states and structural distortion in highly compressed multiferroic TbMnO3 was probed by x-ray diffraction (XRD) and x-ray absorption spectroscopy (XAS) using synchrotron radiation. Refined XRD data enabled observation of a reduced local Jahn-Teller (JT) distortion of Mn sites within MnO6 octahedra in TbMnO3 with increasing hydrostatic pressure. A progressively increasing intensity of the white line in Mn K-edge x-ray absorption spectra of TbMnO3 was detected with increasing pressure. The absorption threshold of Mn K-edge spectra of TbMnO3 is shifted toward higher energy, whereas the pre-edge peak is slightly shifted to lower energy with increasing hydrostatic pressure. We provide spectral evidence for pressure-induced bandwidth broadening for mangnites. The enhanced intensity of the white line and the shifted absorption threshold of Mn K-edge spectra are explained in terms of a reduced JT distortion of MnO6 octahedra in compressed TbMnO3. Comparison of XAS data with full-multiple-scattering calculations using code FDMNES shows satisfactory agreement between experimental and calculated Mn K-edge spectra.