Stripe antiferromagnetic correlations inLaFeAsO1−xFxprobed byA

NMR Study of Superconductivity and Spin Fluctuations in Hole-Doped Superconductor Ca 1− x Na x Fe 2 As 2 ( T

“…. Previous NMR studies on Fe superconductors [42,43] show that strong stripe AFM spin fluctuations lead Our experimental evidences for singlet pairing and spin fluctuations are consistent with many electron and the hole-doped iron pnictides with lower dopings [6,7,42,[44][45][46][47] . It is surprising, however, to see prominent low-energy spin fluctuations under such a large nominal doping (0.33 hole/Fe).…”

NMR investigation of the iron-based superconductors Ca4(Mg,Ti)3Fe2AsTomita1, Kotegawa2, Tao3 et al. 2012Phys. Rev. B

“…[29] Even in the La1111 system with moderate temperature dependence of 1/T 1 T , the anisotropy of 1/T 1 T has been understood to originate in the stripe-type AF spin fluctuation. [34] In addition to the present results, the moderate temperature dependence in 1/T 1 T has been also observed in Sr 4 (Mg,Ti) 2 Fe 2 As 2 O 6−y whose a-axis length is relatively longer. [33] The strong enhancement of 1/T 1 T has been reported in Ca 4 Al 2 Fe 2 As 2 O 6−y with the quite shorter aaxis length.…”

Relationship between Superconductivity and Antiferromagnetism in LaFe(As1−xPx)O Revealed by 31P-NMR

“…10,[12][13][14][15][16] On the other hand, superconductivity is linked not to the low-energy AFM fluctuations probed by NMR spectroscopy but to the local stripe spin correlation with Q stripe = (π, 0) (unfolded Brillouin zone) in LaFeAs(O 1−x F x ). [17][18][19][20] It seems that the roles of AFM fluctuations in superconductivity are different between the "122" and "1111" systems. However, in the "1111" system, most experiments have been performed on the electron-doped system.…”