Similar zone-center gaps in the low-energy spin-wave spectra of NaFeAs and BaFe2As2

Abstract

We report results of inelastic-neutron-scattering measurements of low-energy spin-wave excitations in two structurally distinct families of iron-pnictide parent compounds: Na(1-δ)FeAs and BaFe2As2. Despite their very different values of the ordered magnetic moment and Néel temperatures, T_N, in the antiferromagnetic state both compounds exhibit similar spin gaps of the order of 10 meV at the magnetic Brillouin-zone center. The gap opens sharply below T_N, with no signatures of a precursor gap at temperatures between the orthorhombic and magnetic phase transitions in Na(1-δ)FeAs. We also find a relatively weak dispersion of the spin-wave gap in BaFe2As2 along the out-of-plane momentum component, q_z. At the magnetic zone boundary (q_z = 0), spin excitations in the ordered state persist down to 20 meV, which implies a much smaller value of the effective out-of-plane exchange interaction, J_c, as compared to previous estimates based on fitting the high-energy spin-wave dispersion to a Heisenberg-type model.

5 pages, 4 figures, 1 table

References in corpus (22)

• Superconductivity at 38 K in the iron arsenide (Ba1-xKx)Fe2As2
• High-temperature superconductivity in iron-based materials
• Magnetic order in BaFe2As2, the parent compound of the FeAs based superconductors in a new structural family
• Theory of Electron Nematic Order in LaOFeAs
• Thorium-doping induced superconductivity up to 56 K in Gd1-xThxFeAsO
• Lattice and magnetic instabilities in CaFe2As2: A single crystal neutron diffraction study
• Magnetism in Fe-based superconductors
• Commensurate Itinerant Antiferromagnetism in BaFe2As2: 75As-NMR Studies on a Self-Flux Grown Single Crystal
• Structure, antiferromagnetism and superconductivity of the layered iron arsenide NaFeAs
• Spin and Lattice Structure of Single Crystal SrFe2As2
• A neutron scattering study of the interplay between structure and magnetism in Ba(Fe${}_{1-x}$Co${}_x$)${}_2$As${}_2$
• Low energy spin waves and magnetic interactions in SrFe${}_2$As${}_2$
• Itinerant magnetic excitations in antiferromagnetic CaFe2As2
• Anisotropic itinerant magnetism and spin fluctuations in BaFe2As2: A neutron scattering study
• Symmetry of spin excitation spectra in the tetragonal paramagnetic and superconducting phases of 122-ferropnictides
• High energy spin excitations in BaFe2As2
• Anisotropic three-dimensional magnetism in CaFe2As2
• Interplay between magnetic properties and Fermi surface nesting in iron pnictides
• Competing magnetic ground states in non-superconducting Ba(Fe1-xCrx)2As2
• Columnar magnetic structure coupled with orthorhombic distortion in the antiferromagnetic iron arsenide SrFe${}_2$As${}_2$
• Synthesis, anisotropy, and superconducting properties of LiFeAs single crystal
• Suppression of antiferromagnetic order and orthorhombic distortion in superconducting Ba(Fe0.961Rh0.039)2As2

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• Spin excitations in optimally P-doped BaFe2(As0.7P0.3)2superconductor
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• Orbital-selective coherence-incoherence crossover and metal-insulator transition in Cu-doped NaFeAs