Glasslike excitations in single crystalline Sr8Ga16Ge30 clathrates

被引：28

作者：

Keppens, V ^{[1
]}

McGuire, MA

Teklu, A

Laermans, C

Sales, BC

Mandrus, D

Chakoumakos, BC

机构：

[1] Univ Mississippi, Natl Ctr Phys Acoust, University, MS 38677 USA

[2] Univ Mississippi, Dept Phys, University, MS 38677 USA

[3] Katholieke Univ Leuven, Dept Phys, B-3001 Louvain, Belgium

[4] Oak Ridge Natl Lab, Div Solid State, Oak Ridge, TN 37831 USA

来源：

PHYSICA B-CONDENSED MATTER | 2002年 / 316卷

关键词：

elastic properties; tunneling states; clathrates;

D O I：

10.1016/S0921-4526(02)00431-3

中图分类号：

O469 [凝聚态物理学];

学科分类号：

070205 ;

摘要：

Low-temperature ultrasonic attenuation and resonant ultrasound spectroscopy (RUS) data are reported on single crystals of the semiconductor Sr8Ga16Ge30. The attenuation shows a strikingly glasslike behavior, implying that the elastic properties of the clathrate crystal at low temperatures (T < 1 K) are dominated by the presence of tunneling states. At slightly higher temperatures, the RUS data reflect the presence of a 2-level system with an energy-spacing of 45 K. The origin of these low-energy excitations is found in the 'rattling' Sr-atom, which occupies a fourfold split site in the clathrate structure. (C) 2002 Elsevier Science B.V. All rights reserved.

引用

页码：95 / 100

页数：6

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