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ID 31971
file
creator
Mori, Tatsuya
Iwamoto, K.
Kushibiki, S.
Honda, H.
Matsumoto, Hideki
Toyota, Naoki
Avila, ​Marcos A.
NDC
Physics
description
We present optical conductivity studies of the type-I clathrate Ba_8Ga_<16>Sn_<30>, using a terahertz time-domain spectrometer (0.3-3.0 THz). The lowest-lying spectral peak at 0.72 THz due to the Ba(2) ion's off-center vibration in the oversized cage shows a drastic and anomalous temperature dependence. Below about 100 K, the single broad peak splits into two subpeaks, and with further lowering of the temperature, the spectral shape of this so-called rattling phonon shows non-Boltzmann broadening to the point that the linewidth becomes comparable to the peak frequency. Whereas the initial splitting can be understood by assuming a multiwell anharmonic potential, the strong linewidth broadening toward low temperature cannot, since the Boltzmann factor generally sharpens the low-temperature spectra. The observed behavior suggests strong interaction between the local anharmonic phonons and other excitations.
journal title
Physical review letters
volume
Volume 106
issue
Issue 1
start page
015501-1
end page
015501-4
date of issued
2011-01-06
publisher
The American Physical Society
issn
0031-9007
ncid
publisher doi
language
eng
nii type
Journal Article
HU type
Journal Articles
DCMI type
text
format
application/pdf
text version
publisher
rights
Copyright (c) 2011 The American Physical Society
relation url
department
Graduate School of Advanced Sciences of Matter