Antiferromagnetic Spin Fluctuations and Unconventional Nodeless Superconductivity in an Iron-Based New Superconductor (Ca4Al2O6−y)(Fe2As2): As75 Nuclear Quadrupole Resonance Study
H. Kinouchi, H. Mukuda, M. Yashima, Y. Kitaoka, P. M. Shirage, H. Eisaki, A. Iyo
DOI 10.1103/PhysRevLett.107.047002 · Physical Review Letters
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Abstract
We report As75 nuclear quadrupole resonance studies on (Ca4Al2O6−y)(Fe2As2) with Tc=27 K. Measurement of nuclear-spin-relaxation rate 1/T1 has revealed a significant development of two-dimensional antiferromagnetic spin fluctuations down to Tc in association with the smallest As-Fe-As bond angle. Below Tc, the temperature dependence of 1/T1 without any trace of the coherence peak is well accounted for by a nodeless s±-wave multiple-gaps model. From the fact that its Tc is comparable to Tc=28 K in the optimally doped LaFeAsO1−y in which antiferromagnetic spin fluctuations are not dominant, we remark that antiferromagnetic spin fluctuations are not a unique factor for enhancing Tc among Fe-based superconductors, but a condition for optimizing superconductivity should be addressed from the lattice structure point of view.
Source-reported materials — not catalogue approval
| Formula | Reported Tc (K) | Pressure (GPa) | Type |
|---|---|---|---|
| (Ca4Al2O6-y)(Fe2As2) Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | 27 | Pressure not reported | onset |
| [Ca4(Mg0.25Ti0.75)3Oy](Fe2As2) Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | 47 | Pressure not reported | unknown |
| (Sr4V2O6)(Fe2As2) Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | 37 | Pressure not reported | unknown |
| LaFeAsO1-y Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | 28 | Pressure not reported | unknown |
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