Two distinct superconducting states in KFe2As2 under high pressure
Taichi Terashima, Kunihiro Kihou, Kaori Sugii, Naoki Kikugawa, Takehiko Matsumoto, Shigeyuki Ishida, Chul-Ho Lee, Akira Iyo, Hiroshi Eisaki, Shinya Uji
DOI 10.1103/PhysRevB.89.134520 · Physical Review B
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Abstract
We report measurements of ac magnetic susceptibility χac and de Haas–van Alphen (dHvA) oscillations in KFe2As2 under high pressure up to 24.7 kbar. The pressure dependence of the superconducting transition temperature Tc changes from negative to positive across Pc∼18 kbar, as previously reported. The ratio of the upper critical field to Tc, i.e., Bc2/Tc, is enhanced above Pc, and the shape of the χac versus field curves qualitatively changes across Pc. dHvA oscillations smoothly evolve across Pc, indicating no drastic change in the Fermi surface up to 24.7 kbar. Three dimensionality increases with pressure, while effective masses show decreasing trends. We suggest a crossover from a nodal to a full-gap s wave as a possible explanation.
Source-reported materials — not catalogue approval
| Formula | Reported Tc (K) | Pressure (GPa) | Type |
|---|---|---|---|
| KFe2As2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | — | Pressure unresolved | unknown |
| KFe2As2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | — | 2.47 GPa | unknown |
| LaFeAs(O,F) Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | 26 | Pressure not reported | unknown |
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