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Author  |
Fasano, Y.; Szabó, P.; KaÄmarÄík, J.; Pribulová, Z.; Pedrazzini, P.; Samuely, P.; Correa, V.F. |
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Title |
Unconventional superconductivity in the strong-coupling limit for the heavy fermion system CeCoIn5 |
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Journal Article |
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Year |
2018 |
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Physica B: Condensed Matter |
Abbreviated Journal |
Physica B |
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536 |
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798-802 |
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Heavy fermion superconductors; Scanning tunneling spectroscopy; Superconducting phase; Pseudogap phase |
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Abstract |
We present scanning tunneling spectroscopy measurements of the local quasiparticles' excitation spectra of the heavy fermion CeCoIn5 between 440mK and 3K in samples with a bulk Tc=2.25K. The spectral shape of our low-temperature tunneling data, quite textbook nodal-Δ conductance, allow us to confidently fit the spectra with a d-wave density of states considering also a shortening of quasiparticles' lifetime term Γ. The Δ(0) value obtained from the fits yields a BCS ratio 2Δ/kTc=7.73 suggesting that CeCoIn5 is an unconventional superconductor in the strong coupling limit. The fits also reveal that the height of coherence peaks in CeCoIn5 is reduced with respect to a pure BCS spectra and therefore the coupling of quasiparticles with spin excitations should play a relevant role. The tunneling conductance shows a depletion at energies smaller than Δ for temperatures larger than the bulk Tc, giving further support to the existence of a pseudogap phase that in our samples span up to T*∼1.2Tc. The phenomenological scaling of the pseudogap temperature observed in various families of cuprates, 2Δ/kT*∼4.3, is not fulfilled in our measurements. This suggests that in CeCoIn5 the strong magnetic fluctuations might conspire to close the local superconducting gap at a smaller pesudogap temperature-scale than in cuprates. |
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0921-4526 |
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BT @ pedrazp @ |
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766 |
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