Observation of a van Hove singularity and implication for strong coupling induced Cooper pairing in KFe2As2
Abstract
Scanning tunneling spectroscopy (STS) and angle-resolved photoemission spectroscopy (ARPES) have been investigated on single crystal samples of KFe2As2. A van Hove singularity (vHs) has been directly observed just a few meV below the Fermi level EF of superconducting KFe2As2, which locates in the middle of the principle axes of the first Brillouin zone. The majority of the density-of-states at EF, mainly contributed by the proximity effect of the saddle point to EF, is non-gapped in the superconducting state. Our observation of nodal behavior of the momentum area close to the vHs points, while providing consistent explanations to many exotic behaviours previously observed in this material, suggests Cooper pairing induced by a strong coupling mechanism.
Turn this paper into a lesson
ArcXiv compiles a structured reading guide from this paper's metadata: plain-English importance, contributions, prerequisite concepts, which sections to read first, flashcards, and a quiz. Grounded in the abstract, never invented.