Impurity-induced bound states as a signature of pairing symmetry in multiband superconducting CeCu2Si2

Abstract

The notion of multiband superconductivity with dominant two-gap features has been recently applied to the unconventional superconductor CeCu2Si2 for challenging the previously accepted concept of nodal d-wave pairing. In the proposed study, the realistic multiband Fermi surface topology of CeCu2Si2 was obtained through first-principles calculations, and analysis was conducted with an effective two-band hybridization model including detailed band structure. Within the T-matrix approximation, the obtained calculation results show that different pairing candidates, including fully gapped s-wave, loop-nodal s-wave, and d-wave pairings, could yield qualitatively distinct features characterized by impurity-induced bound states. These features can be verified through high-resolution scanning tunneling microscopy or spectroscopy and provide corroborative justification that would be beneficial for the ongoing research regarding the superconducting gap symmetry of CeCu2Si2 at ambient pressure.

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Acknowledgements

This work was supported by the National Natural Science Foundation of China under Grant Nos. 11774025, 11774401, and 11522435. Y. Y. was also supported by the National Key R&D Program of China (Grant No. 2017YFA0303103) and the Strategic Priority Research Program (B) of the Chinese Academy of Sciences (Grant No. XDB07020200). S. F. was supported by the National Key R&D Program of China (Grant No. 2016YFA0300304).

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Correspondence to Bin Liu or Yi-Feng Yang.

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Wang, D., Liu, B., Liu, M. et al. Impurity-induced bound states as a signature of pairing symmetry in multiband superconducting CeCu2Si2. Front. Phys. 14, 13501 (2019). https://doi.org/10.1007/s11467-018-0852-5

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Keywords

  • heavy-fermion superconductivity
  • pairing symmetry
  • impurity effect
  • local density of states