Anomalous Attenuation of Piezoacoustic Surface Waves by Liquid Helium Thin Films
Anomalous Attenuation of Piezoacoustic Surface Waves by Liquid Helium Thin Films
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DOI：
10.1007/s10909-018-02115-0
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发表时间：
2019-05-01
影响因子：
2
通讯作者：
Pollanen, J.
中科院分区：
文献类型：
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作者：
Byeon, H.;Nasyedkin, K.;Pollanen, J.
我们报告的观察到的异常高衰减的高频表面声波的液体4He薄膜。压电声波沿着涂覆有不同量的液氦的锂酸盐衬底的表面传播。当氦层的厚度远大于衬底上的表面声波的波长时，其衰减主要由压缩波的激发进入液体，与理论和先前的测量结果很好地一致。然而，对于足够薄的氦气覆盖，我们发现，声波衰减显着增加超过与衬底浸没在散装液体中测量。这种增强衰减的可能机制进行了讨论。
We report on the observation of an anomalously high attenuation of high-frequency surface acoustic waves by thin films of liquid 4He. The piezoelectric acoustic waves propagate along the surface of a lithium niobate substrate, which is coated with varying amounts of liquid helium. When the thickness of the helium layer is much larger than the wavelength of the surface acoustic wave on the substrate, its attenuation is dominated by the excitation of compressional waves into the liquid, in good agreement with theory and previous measurements. However, for sufficiently thin helium coverage, we find that the acoustic wave attenuation is significantly increased beyond that measured with the substrate submerged in bulk liquid. Possible mechanisms for this enhanced attenuation are discussed.