Electronic properties of LaOFFeAs in the normal state probed by NMR/NQR

Abstract

We report 139La, 57Fe and 75As nuclear magnetic resonance (NMR) and nuclear quadrupole resonance (NQR) measurements on powders of the new LaO1-xFxFeAs superconductor for x = 0 and x = 0.1 at temperatures up to 480 K, and compare our measured NQR spectra with local density approximation (LDA) calculations. For all three nuclei in the x = 0.1 material, it is found that the local Knight shift increases monotonically with an increase in temperature, and scales with the macroscopic susceptibility, suggesting a single magnetic degree of freedom. Surprisingly, the spin lattice relaxation rates for all nuclei also scale with one another, despite the fact that the form factors for each site sample different regions of q-space. This result suggests a lack of any q-space structure in the dynamical spin susceptibility that might be expected in the presence of antiferromagnetic correlations. Rather, our results are more compatible with simple quasi-particle scattering. Furthermore, we find that the increase in the electric field gradient at the As cannot be accounted for by LDA calculations, suggesting that structural changes, in particular the position of the As in the unit cell, dominate the NQR response.

arXiv comment17 pages, 6 figures

References in corpus (20)

• Magnetic Order versus superconductivity in the Iron-based layered La(O1-xFx)FeAs systems
• LaFeAsO${}_{1-x}$F${}_x$: A low carrier density superconductor near itinerant magnetism
• The challenge of unravelling magnetic properties in LaFeAsO
• Evolution from Itinerant Antiferromagnet to Unconventional Superconductor with Fluorine Doping in La(O_{1-x}F_{x})FeAs Revealed by ^{75}As and ^{139}La Nuclear Magnetic Resonance
• Commensurate Spin Density Wave in LaOFeAs: A Local Probe Study
• ${}^{75}$As NMR studies of superconducting LaO${}_{0.9}$F${}_{0.1}$FeAs
• Anisotropy in the electrical resistivity and susceptibility of superconducting BaFe${}_2$As${}_2$ single crystals
• Iron-based layered superconductor LaO${}_{1-x}$F${}_x$FeAs: an antiferromagnetic semimetal
• Magnetic and structural transitions in layered FeAs systems: AFe2As2 versus RFeAsO compounds
• Bandwidth and Fermi surface of Iron-Oxypnictides: covalency and sensitivity to structural changes
• Field and Temperature Dependence of the Superfluid Density in LaO_{1-x}F_xFeAs Superconductors: A Muon Spin Relaxation Study
• Superconductivity at 53.5 K in GdFeAsO1-delta
• 19-F NMR Investigation of Iron-pnictide Superconductor LaFeAsO(0.89)F(0.11)
• 75As NQR/NMR Studies on Oxygen-deficient Iron-based Oxypnictide Superconductors LaFeAsO_{1-y} (y=0,0.25,0.4) and NdFeAsO_{0.6}
• 59Co NMR study of the Co states in superconducting and anhydrous cobaltates
• The Delicate Electronic and Magnetic Structure of the LaOFePn System (Pn = pnictogen)
• Spin Fluctuations and Unconventional Superconductivity in the Fe-based Oxypnictide Superconductor LaFeAsO_0.7 probed by 57Fe-NMR
• Synthesis and physical properties of $\mathbf{La}{\mathbf{O}}_{1-\mathbf{x}}{\mathbf{F}}_{\mathbf{x}}\mathbf{FeAs}$
• Electronic properties of LaOFFeAs in the normal state probed by NMR/NQR
• Local antiferromagnetic correlations in the iron pnictide superconductors LaFeAsO{1-x}F{x} and Ca(Fe,Co)2As2 as seen via normal-state susceptibility

Cited by in corpus (21)

• Why Does Undoped FeSe Become A High Tc Superconductor Under Pressure?
• Hall effect and resistivity study of the magnetic transition, carrier content and Fermi liquid behavior in Ba(Fe(1-x) Cox)2As2
• Crystal and magnetic structure of the oxypnictide superconductor LaO(1-x)FxFeAs: evidence for magnetoelastic coupling
• Fishtail effect and vortex dynamics in LiFeAs single crystals
• Nanoscale electronic order in iron pnictides
• A perspective on pnictide superconductors
• Antiferromagnetic fluctuations in the normal state of LiFeAs
• Density Functional Study of the Over-Doped Iron Chalcogenide: TlFe${}_2$Se${}_2$ with ThCr${}_2$Si${}_2$ structure
• Progressive slowing down of spin fluctuations in underdoped LaFeAsO${}_{1-x}$F${}_x$
• The poisoning effect of Mn in LaFe(1-x)Mn(x)AsO(0.89)F(0.11): unveiling a quantum critical point in the phase diagram of iron-based superconductors
• Electronic properties of LaOFFeAs in the normal state probed by NMR/NQR
• 75As NMR-NQR study in superconducting LiFeAs
• Bandwidth controlled insulator-metal transition in BaFe${}_2$S${}_3$: A Mössbauer study under pressure
• Superconducting properties and pseudogap from preformed Cooper pairs in the triclinic (CaFe${}_{1-x}$Pt${}_x$As)${}_{10}$Pt${}_3$As${}_8$
• Local nematic susceptibility in stressed BaFe${}_2$As${}_2$ from NMR electric field gradient measurements
• Breakdown of single spin-fluid model in heavily hole-doped superconductor CsFe2As2
• Experimental evidence of $T_c$ enhancement without the influence of spin fluctuations: NMR study on LaFeAsO_{1-x}H_x under a pressure of 3.0 GPa
• High-Tc Nodeless s_\pm-wave Superconductivity in (Y,La)FeAsO_{1-y} with Tc=50 K: 75As-NMR Study
• A unified phase diagram of F-doped LaFeAsO by means of NMR and NQR parameters
• Nematicity in LaFeAsO${}_{1-x}$F${}_x$
• Nematicity in LaFeAsO single crystals studied by elastoresistance, high-resolution thermal expansion and shear-modulus measurements