Thermodynamic evidence for a two-component superconducting order parameter in Sr2RuO4
Thermodynamic evidence for a two-component superconducting order parameter in Sr2RuO4
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DOI：
10.1038/s41567-020-1032-4
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发表时间：
2020-09-21
期刊：
影响因子：
19.6
通讯作者：
Ramshaw, B. J.
中科院分区：
文献类型：
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作者：
Ghosh, Sayak;Shekhter, Arkady;Ramshaw, B. J.
Sr2RuO4作为自旋三重态超导体的主要候选材料已经存在了26年1。然而，最近的核磁共振实验对这种候选性提出了质疑（2,3），很难找到一个与所有实验一致的超导理论。因此，这种材料的序参数对称性仍然是一个悬而未决的问题。需要基于对称性的实验来排除大量可能的超导序参数。在这里，我们使用共振超声光谱测量了Sr2RuO4通过超导跃迁的整个对称分辨弹性张量。我们观察到剪切弹性模量c（66）的热力学不连续，这意味着超导序参量有两个分量。双分量p波阶参量，如p(x) + ip(y)，自然满足这一要求。由于这个顺序参数似乎已经被最近的核磁共振实验排除，我们建议另外两个双组分顺序参数，即{d(xz)；D (yz)}和{D (x2-y2)；g(xy(x2 -y2))}，现在是Sr2RuO4的序参量的主要候选者。
Sr2RuO4 has stood as the leading candidate for a spin-triplet superconductor for 26 years1. However, recent NMR experiments have cast doubt on this candidacy(2,3) and it is difficult to find a theory of superconductivity that is consistent with all experiments. The order parameter symmetry for this material therefore remains an open question. Symmetry-based experiments are needed that can rule out broad classes of possible superconducting order parameters. Here, we use resonant ultrasound spectroscopy to measure the entire symmetry-resolved elastic tensor of Sr2RuO4 through the superconducting transition. We observe a thermodynamic discontinuity in the shear elastic modulus c(66), which implies that the superconducting order parameter has two components. A two-component p-wave order parameter, such as p(x) + ip(y), naturally satisfies this requirement. As this order parameter appears to have been precluded by recent NMR experiments, we suggest that two other two-component order parameters, namely {d(xz); d(yz)} and {d(x2-y2); g(xy(x2 -y2))},, are now the prime candidates for the order parameter of Sr2RuO4.