Temperature and Concentration Relaxation in Phase-separated Superfluid 3He鈥?sup>4He Mixtures
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- 作者：G. Sheshin ; T. Kalko ; K. Nemchenko ; E. Rudavskii ; V. Chagovets and A. Zadorozhko
- 关键词：nucleation ; phase separation ; relaxation ; superfluid 3 He– ; 4He mixture
- 刊名：Journal of Low Temperature Physics
- 出版时间：February, 2007
- 出版年：2007
- 期刊代码：20_00222291
- 类别：law
- 卷：146
- 期：3-4
- 页码：403-416
- 数据来源：sp
摘要
The kinetics of the temperature and concentration variations in the superfluid 3He–4He mixtures with initial concentration of 9.8%3He, and heated from below, was studied experimentally under the pressure of 0.38 bar over a temperature range of 150–400 mK. It is found that in contrast to homogeneous liquids, the temperature and concentration relaxation in phase-separated mixtures can be described by a superposition of two exponential processes in which the time constants of temperature and concentration variations coincide. If the initial mixture was homogeneous and phase separation was triggered by a heat flow, the temperature and concentration vary non-monotonically and exhibit anomalous features at the moment of phase separation. In this case the phase transition starts in the metastable superfluid, formed out of a quite supersaturated mixture where the nucleation of the new phase may be caused by quantized vortices. The results are analyzed in terms of two possible mechanisms of relaxation–the acoustic mechanism with the second sound velocity and the diffusive one connected with dissipative flows of impurity and thermal excitations. It is shown that the measured relaxation times agree with a prediction of the theory.