Observation of a Dislocation-Related Interfacial Friction Mechanism in Mobile Solid $$^{4}$$4He
Observation of a Dislocation-Related Interfacial Friction Mechanism in Mobile Solid $$^{4}$$4He
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移动固体中与位错相关的界面摩擦机制的观察 $$^{4}$$4He
DOI：
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发表时间：
2012
期刊：
影响因子：
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通讯作者：
E. Polturak
中科院分区：
文献类型：
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作者：
A. Eyal;E. Livne;E. Polturak
我们报告的温度和应力的摩擦与固体$^{4}$$4 He的微晶在彼此接触的相对运动的依赖性的研究。在扭转振荡器（TO）的环形样品空间内包含的单晶的无序化期间，自发地出现存在这种运动的情况。在TO振荡壁施加的扭矩下，这些微晶相对于彼此移动，在其界面处产生可测量的耗散。我们研究了从商业纯的$$^{4}$$4He和从100 ppm的$$^{3}$$3He-$^{4}$$4He混合物生长的固体样品中在0.5和1.8 K之间的摩擦。通过将TO建模为驱动谐振子来分析数据。在这个模型中，分析的谐振频率和振幅的TO产生的摩擦系数的温度依赖性。通过将数据拟合到特定形式，我们发现在我们的温度范围内，与微晶的界面运动相关的主要摩擦机制来自于单个位错的爬升。与这种摩擦相关的特征能量标度可以是3或6 K，这取决于样品。固体在这种摩擦力作用下的运动也许可以说是“滑-粘”运动的下限。
We report a study of the temperature and stress dependence of the friction associated with a relative motion of crystallites of solid $$^{4}$$4He in contact with each other. A situation where such motion exists emerges spontaneously during a disordering of a single crystal contained inside an annular sample space of a torsional oscillator (TO). Under the torque applied by the oscillating walls of the TO these crystallites move relative to each other, generating measurable dissipation at their interface. We studied this friction between 0.5 and 1.8 K in solid samples grown from commercially pure $$^{4}$$4He and from a 100 ppm $$^{3}$$3He–$$^{4}$$4He mixture. The data were analyzed by modeling the TO as a driven harmonic oscillator. In this model, an analysis of the resonant frequency and amplitude of the TO yields the temperature dependence of the friction coefficient. By fitting the data to specific forms, we found that over our temperature range, the dominant friction mechanism associated with the interfacial motion of the crystallites results from climb of individual dislocations. The characteristic energy scale associated with this friction can be 3 or 6 K, depending on the sample. The motion of the solid in the presence of such friction can perhaps be described as the low limit of “slip–stick” motion.