Impurity-induced bound states as a signature of pairing symmetry in multiband superconducting CeCu2Si2
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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.
Keywordsheavy-fermion superconductivity pairing symmetry impurity effect local density of states
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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