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ID 18722
本文ファイル
著者
Nagai, Shinji
Okamoto, Naoki
Iga, Fumitoshi
Kunii, Satoru
抄録(英)
The excitation-energy, polarization, and temperature dependeces of Raman scattering spectra have been measured for the RB6 crystals (R=Ca 2+, La3+, Ce3+, Pr3+, Sm 2.6+, Gd3+, Dy3+, and Yb2+). In the divalent crystals of CaB6 and YbB6, the Eg phonon shows doublet, while the line shape is a broad single peak for the trivalent case. In the trivalent crystals, two kinds of the extra peaks have been clearly observed at around 200 cm-1 and at around 1400 cm -1 in addition to the Raman-active phonons and crystal electric-field (CEF) excitations. The peak intensities at around 200 cm -1 show the anomalous decrease with decreasing temperature, and this temperature dependence correlates with that of the mean-square displacement of the R ion. Furthermore, their energies decrease with the increase of the cage space due to B6. These peaks are originated from the second-order excitation of acoustic phonons. The broad peak at around 1400 cm-1 is assigned as the second-order excitation of the T2g phonon. For the T2g phonon, the energy difference and its line-shape change between the trivalent and divalent crystals suggests the existence of electron-phonon interaction. We have observed the CEF excitation in PrB 6 and have obtained the Lea, Leask, and Wolf parameters with x=0.94 and W=9.2 K.
掲載誌名
Physical Review B - Condensed Matter and Materials Physics
68巻
22号
開始ページ
224305-1
終了ページ
224305-9
出版年月日
2003-12-30
出版者
American Physical Society
ISSN
0163-1829
NCID
出版者DOI
言語
英語
NII資源タイプ
学術雑誌論文
広大資料タイプ
学術雑誌論文
DCMIタイプ
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フォーマット
application/pdf
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権利情報
Copyright (c) 2003 American Physical Society.
関連情報URL
部局名
総合科学研究科
先端物質科学研究科