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arXiv 1606.01050cond-mat.supr-con
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拓扑超导体beta-PdBi2中的全能隙超导电性

Fully gapped superconductivity in the topological superconductor beta-PdBi2

P. K. Biswas, D. G. Mazzone, R. Sibille, E. Pomjakushina, K. Conder, H. Luetkens, C. Baines, J. L. Gavilano, M. Kenzelmann, A. Amato, E. Morenzoni

摘要:

最近在PdBi 2 β相中发现的拓扑保护表面态重新点燃了这类超导体的研究兴趣。在这里,我们展示了我们的μ子自旋弛豫和旋转(μ SR)测量进行调查的超导和磁性能和拓扑效应的超导基态的β-PdBi 2的结果。零场muSR数据显示,没有相当大的自发磁化与超导性的发病意味着时间反转对称性被保存在β-PdBi 2的超导状态。此外,在横向场(TF)muSR实验中已经观察到所施加的场的强抗磁位移,这表明任何三重态配对通道(如果存在的话)都不会主导超导冷凝物。利用TF-muSR,我们估计在零温度下的磁穿透深度为263(10)nm。磁穿透深度的温度依赖性为零温下0.78(1)meV的无节点单s波型各向同性能隙的存在提供了证据。我们的研究结果进一步表明,拓扑保护的表面状态对超导体的体积没有影响。

英文摘要:

The recent discovery of the topologically protected surface states in the beta-phase of PdBi2 has reignited the research interest in this class of superconductors. Here, we show results of our muon spin relaxation and rotation (muSR) measurements carried out to investigate the superconducting and magnetic properties and the topological effect in the superconducting ground state of beta-PdBi2. Zero-field muSR data reveal that no sizeable spontaneous magnetization arises with the onset of superconductivity implying that the time reversal symmetry is preserved in the superconducting state of beta-PdBi2. Further, a strong diamagnetic shift of the applied field has been observed in the transverse-field (TF) muSR experiments, indicating that any triplet-pairing channel, if present, does not dominate the superconducting condensate. Using TF-muSR, we estimate that the magnetic penetration depth is 263(10) nm at zero temperature. Temperature dependence of the magnetic penetration depth provides evidence for the existence of a nodeless single s-wave type isotropic energy gap of 0.78(1) meV at zero temperature. Our results further suggest that the topologically protected surface states have no effect on the bulk of the superconductor.

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