TY - JOUR
T1 - Lattice instability and elastic dispersion due to the rattling motion in the type-I clathrate Ba 8Ga 16Sn 30
AU - Ishii, Isao
AU - Suetomi, Yasuhiko
AU - Fujita, Takahiro K.
AU - Suekuni, Koichiro
AU - Tanaka, Tomoo
AU - Takabatake, Toshiro
AU - Suzuki, Takashi
AU - Avila, Marcos A.
PY - 2012/2/7
Y1 - 2012/2/7
N2 - To investigate the off-center rattling motion and its charge-carrier dependence in type-I clathrate compounds, we carried out ultrasonic measurements on type-I Ba 8Ga 16Sn 30 and a reference compound, K 8Ga 8Sn 38. We found elastic softening of C 44 originating from a lattice instability due to the off-center rattling motion of Ba atom in Ba 8Ga 16Sn 30. Elastic softening below 1 K suggests that the lattice instability remains at very low temperatures. We also found ultrasonic dispersion which has no mode selectivity. No-mode-selective ultrasonic dispersion in Ba 8Ga 16Sn 30 would be caused by a strong electron-phonon coupling. No charge-carrier dependence is observed between n-type and p-type Ba 8Ga 16Sn 30. The significant softening on the bulk modulus in Ba 8Ga 16Sn 30 contrasts to the continuous hardening in K 8Ga 8Sn 38, indicating the central role of the rattling motion in the softening.
AB - To investigate the off-center rattling motion and its charge-carrier dependence in type-I clathrate compounds, we carried out ultrasonic measurements on type-I Ba 8Ga 16Sn 30 and a reference compound, K 8Ga 8Sn 38. We found elastic softening of C 44 originating from a lattice instability due to the off-center rattling motion of Ba atom in Ba 8Ga 16Sn 30. Elastic softening below 1 K suggests that the lattice instability remains at very low temperatures. We also found ultrasonic dispersion which has no mode selectivity. No-mode-selective ultrasonic dispersion in Ba 8Ga 16Sn 30 would be caused by a strong electron-phonon coupling. No charge-carrier dependence is observed between n-type and p-type Ba 8Ga 16Sn 30. The significant softening on the bulk modulus in Ba 8Ga 16Sn 30 contrasts to the continuous hardening in K 8Ga 8Sn 38, indicating the central role of the rattling motion in the softening.
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U2 - 10.1103/PhysRevB.85.085101
DO - 10.1103/PhysRevB.85.085101
M3 - Article
AN - SCOPUS:84863273495
VL - 85
JO - Physical Review B - Condensed Matter and Materials Physics
JF - Physical Review B - Condensed Matter and Materials Physics
SN - 1098-0121
IS - 8
M1 - 085101
ER -