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arXiv · 0810.4790

Anisotropic itinerant magnetism and spin fluctuations in BaFe2As2: A neutron scattering study

K. Matan·R. Morinaga·K. Iida·T. J. Sato
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Abstract

Neutron scattering measurements were performed to investigate magnetic excitations in a single-crystal sample of the ternary iron arsenide BaFe2As2, a parent compound of a recently discovered family of Fe-based superconductors. In the ordered state, we observe low energy spin-wave excitations with a gap energy of 9.8(4) meV. The in-plane spin-wave velocity v_ab and out-of-plane spin-wave velocity v_c measured at 12 meV are 280(150) and 57(7) meV A, respectively. At high energy, we observe anisotropic scattering centered at the antiferromagnetic wave vectors. This scattering indicates two-dimensional spin dynamics, which possibly exist inside the Stoner continuum. At T_N=136(1) K, the gap closes, and quasi-elastic scattering is observed above T_N, indicative of short-range spin fluctuations. In the paramagnetic state, the scattering intensity along the L direction becomes "rodlike," characteristic of uncorrelated out-of-plane spins, attesting to the two-dimensionality of the system.

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K. Matan, R. Morinaga, K. Iida, T. J. Sato. 2009-02-13. Anisotropic itinerant magnetism and spin fluctuations in BaFe2As2: A neutron scattering study. https://doi.org/10.1103/physrevb.79.054526

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