Acoustic properties of amorphous silica between 1 and 500 mK

被引：33

作者：

Fefferman, A. D. ^{[1
]}

Pohl, R. O. ^{[1
]}

Zehnder, A. T. ^{[2
]}

Parpia, J. M. ^{[1
]}

机构：

[1] Cornell Univ, Dept Phys, Ithaca, NY 14853 USA

[2] Cornell Univ, Dept Theoret & Appl Mech, Ithaca, NY 14853 USA

来源：

PHYSICAL REVIEW LETTERS | 2008年 / 100卷 / 19期

关键词：

D O I：

10.1103/PhysRevLett.100.195501

中图分类号：

O4 [物理学];

学科分类号：

0702 ;

摘要：

We have made reliable measurements of the sound velocity delta v/v(0) and internal friction Q(-1) in vitreous silica at 1.03, 3.74, and 14.0 kHz between 1 mK and 0.5 K. In contrast with earlier studies that did not span as wide a temperature and frequency range, our measurements of Q(-1) reveal a crossover (as T decreases) only near 10 mK from the T-3 dependence predicted by the standard tunneling model to a T dependence predicted if interactions are accounted for. We find good fits at all frequencies using a single interaction parameter, the prefactor of the interaction-driven relaxation rate, in contrast to earlier claims of a frequency dependent power law. We also show that the discrepancy in the slopes d(delta v/v(0))/d(log(10)T) below and above the sound velocity maximum (1-1 observed, 1-2 predicted) can be resolved by assuming a modified distribution of tunneling states.

引用

页数：4