A Summary of Mass Flux Measurements in Solid 4He
A Summary of Mass Flux Measurements in Solid 4He
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固体 4He 质量通量测量总结
DOI：
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发表时间：
2012
期刊：
影响因子：
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通讯作者：
Y. Vekhov
中科院分区：
文献类型：
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作者：
R. Hallock;M. Ray;Y. Vekhov
在这里，我们总结并简要回顾了马萨诸塞大学阿默斯特分校在低于 28 bar 的样品压力下使用固体 4He 所做的一些工作。这项工作的动机是尝试让 4He 原子穿过固体 4He，而不直接对固体本身施加机械压力。所选择的具体技术仅限于熔化曲线附近的压力，最初设计的目的是为是否可以观察到这种质量通量的问题提供是/否答案。热机械效应和直接质量注入分别用于在两个超流体 4He 储层之间产生化学势差，这两个超流体 4He 储层通过与固体 4He 串联的超流体填充 Vycor 棒相互连接，位于相图的 hcp 区域。热机械效应是一种更通用的方法。并且，在特定的对称应用中，它被设计为提供质量通量，而固体密度几乎没有或没有净增加。我们的观察结果（偏离但接近熔化曲线）包括：（1）随着温度降低到约 650 mK 以下，通过固体填充电池的原子直流通量不断增加，并且没有高于该温度的通量； (2) 在 75-80 mK 附近存在通量最小值和通量不稳定，在较低温度下通量增加； (3) 通量高于 100 mK 的温度依赖性以及通量对净驱动化学势差的依赖性，为导致通量高于 100 mK 的可能机制提供了有趣的见解。最新数据表明，无论何种原因导致固体 4He 中的通量（至少 T>100 mK），都可能是玻色子卢廷格液体的一个例子。
Here we provide a summary and brief review of some of the work done with solid 4He at the University of Massachusetts Amherst below a sample pressure of 28 bar. The motivation for the work has been to attempt to pass 4He atoms through solid 4He without directly applying mechanical pressure to the solid itself. The specific technique chosen is limited to pressures near the melting curve and was initially designed to provide a yes/no answer to the question of whether or not it might be possible to observe such a mass flux. The thermo-mechanical effect and direct mass injection have been separately used to create chemical potential differences between two reservoirs of superfluid 4He connected to each other through superfluid-filled Vycor rods in series with solid 4He, which is in the hcp region of the phase diagram. The thermo-mechanical effect is a more versatile approach. And, in a particular symmetric application it is designed to provide a mass flux with little or no net increase in the density of the solid. Our observations, off but near the melting curve, have included: (1) the presence of an increasing DC flux of atoms through the solid-filled cell with decreasing temperature below ≈650 mK and no flux above this temperature; (2) the presence of a flux minimum and flux instability in the vicinity of 75–80 mK, with a flux increase at lower temperatures; (3) the temperature dependence of the flux above 100 mK and the dependence of the flux on the net driving chemical potential difference provide interesting insights on the possible mechanism that leads to the flux above 100 mK. The most recent data suggest that whatever is responsible for the flux in solid 4He, at least for T>100 mK, may be an example of a Bosonic Luttinger liquid.