Abstract
The interplay between unconventional Cooper pairing and quantum states associated with atomic scale defects is a frontier of research with many open questions. So far, only a few of the high-temperature superconductors allow this intricate physics to be studied in a widely tunable way. We use scanning tunneling microscopy to image the electronic impact of Co atoms on the ground state of the LiFe1-xCoxAs system. We observe that impurities progressively suppress the global superconducting gap and introduce low energy states near the gap edge, with the superconductivity remaining in the strong-coupling limit. Unexpectedly, the fully opened gap evolves into a nodal state before the Cooper pair coherence is fully destroyed. Our systematic theoretical analysis shows that these new observations can be quantitatively understood by the nonmagnetic Born-limit scattering effect in an s±-wave superconductor, unveiling the driving force of the superconductor to metal quantum phase transition.
Originalsprog | Engelsk |
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Artikelnummer | 217004 |
Tidsskrift | Physical Review Letters |
Vol/bind | 123 |
Udgave nummer | 21 |
Antal sider | 7 |
ISSN | 0031-9007 |
DOI | |
Status | Udgivet - 20 nov. 2019 |