Exotic heavy-fermion superconductivity in atomically thin CeCoIn5 films
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We report an in situ scanning tunneling microscopy study of atomically thin films of CeCoIn5, a d-wave heavy-fermion superconductor. Both hybridization and superconducting gaps are observed even in monolayer CeCoIn5, providing direct evidence of superconductivity of heavy quasiparticles mediated by purely two-dimensional bosonic excitations. In these atomically thin films, Tc is suppressed to nearly half of the bulk, but is similar to CeCoIn5/YbCoIn5 superlattices containing CeCoIn5 layers with the same thickness as the thin films. Remarkably, the out-of-plane upper critical field μ0Hc2⊥ at zero temperature is largely enhanced from those of bulk and superlattices. The enhanced Hc2⊥ well exceeds the Pauli and bulk orbital limits, suggesting the possible emergence of unusual superconductivity with parity mixing caused by the inversion symmetry breaking.
Peng , L , Naritsuka , M , Akutagawa , S , Suetsugu , S , Haze , M , Kasahara , Y , Terashima , T , Peters , R , Matsuda , Y & Asaba , T 2023 , ' Exotic heavy-fermion superconductivity in atomically thin CeCoIn 5 films ' , Physical Review B , vol. 107 , no. 4 , L041101 . https://doi.org/10.1103/PhysRevB.107.L041101
Physical Review B
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DescriptionFunding: This work is supported by Grants-in-Aid for Scientific Research (KAKENHI) (Grants No. JP18H01180, No. JP18H05227, and No. JP18K03511) from Japan Society for the Promotion of Science (JSPS), and by Core Research for Evolutional Science and Technology (CREST) (Grant No. JP-MJCR19T5) from Japan Science and Technology Agency (JST).
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