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NMR evidence of strongly correlated superconductivity in LiFeAs: Tuning toward a spin-density-wave ordering

2010; American Physical Society; Volume: 82; Issue: 18 Linguagem: Inglês

10.1103/physrevb.82.180501

1550-235X

Long Ma, Jianhua Zhang, Genfu Chen, Weiqiang Yu,

Rare-earth and actinide compounds

In this letter, we reported the results of NMR study on LiFeAs single crystals. We find a strong evidence of the low temperature spin fluctuations; by changing sample preparation conditions, the system can be tuned toward an spin-density-wave (SDW) quantum-critical point. The detection of an interstitial Li(2) ion, possibly locating in the tetrahedral hole, suggests that the off-stoichiometry and/or lattice defect can probably account for the absence of the SDW ordering in LiFeAs. These facts show that LiFeAs is a strongly correlated system and the superconductivity is likely originated from the SDW fluctuations.