Microkelvin Thermometry with Bose-Einstein Condensates of Magnons and Applications to Studies of the AB Interface in Superfluid He
Microkelvin Thermometry with Bose-Einstein Condensates of Magnons and Applications to Studies of the AB Interface in Superfluid He
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DOI：
10.1007/s10909-014-1173-x
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发表时间：
2014-06-01
影响因子：
2
通讯作者：
Zavjalov, V. V.
中科院分区：
文献类型：
--
作者：
Heikkinen, P. J.;Autti, S.;Zavjalov, V. V.
捕获的玻色-爱因斯坦磁子凝聚体的相干进动是一个敏感的探测器，可以探测到超流体He-B中的磁弛豫过程，直到可以达到的最低温度。我们利用弛豫速率对热准粒子密度的依赖关系，在低于K的温度下在He-B中实现温度测量。与流行的振弦式或石英音叉温度计不同，磁振子凝聚体允许非接触式温度测量，并使独立地原位确定辐射衰减提供的剩余零温度驰豫成为可能。我们用这种基于磁非凝聚的测温方法研究了超流体He的A、B相界面的热阻抗。磁振子凝聚体也是轨道序参数结构的灵敏探测器。这使得我们第一次观察到了两个AB界面湮没的非热特征。
Coherent precession of trapped Bose-Einstein condensates of magnons is a sensitive probe for magnetic relaxation processes in superfluid He-B down to the lowest achievable temperatures. We use the dependence of the relaxation rate on the density of thermal quasiparticles to implement thermometry in He-B at temperatures below K. Unlike popular vibrating wire or quartz tuning fork based thermometers, magnon condensates allow for contactless temperature measurement and make possible an independent in situ determination of the residual zero-temperature relaxation provided by the radiation damping. We use this magnon-condensate-based thermometry to study the thermal impedance of the interface between A and B phases of superfluid He. The magnon condensate is also a sensitive probe of the orbital order-parameter texture. This has allowed us to observe for the first time the non-thermal signature of the annihilation of two AB interfaces.