Similar zone-center gaps in the low-energy spin-wave spectra of NaFeAs and BaFe2As2
| Autor: | Park, J. T., Friemel, G., Loew, T., Hinkov, V., Li, Yuan, Min, B. H., Sun, D. L., Ivanov, A., Piovano, A., Lin, C. T., Keimer, B., Kwon, Y. S., Inosov, D. S. |
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| Rok vydání: | 2012 |
| Předmět: | |
| Zdroj: | Phys. Rev. B 86, 024437 (2012) |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1103/PhysRevB.86.024437 |
| Popis: | 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-{\delta})FeAs and BaFe2As2. Despite their very different values of the ordered magnetic moment and N\'eel 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-{\delta})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. Comment: 5 pages, 4 figures, 1 table |
| Databáze: | arXiv |
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