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arXiv · 1003.1687

Anisotropic and quasipropagating spin excitations in superconducting Ba(Fe0.926Co0.074)2As2

H. -F. Li·C. Broholm·D. Vaknin·R. M. Fernandes·D. L. Abernathy·M. B. Stone·D. K. Pratt·W. Tian·Y. Qiu·N. Ni·S. O. Diallo·J. L. Zarestky·S. L. Bud'ko·P. C. Canfield·R. J. McQueeney
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Abstract

Inelastic neutron scattering from superconducting (SC) Ba(Fe$_{0.926}$Co$_{0.074}$)$_2$As$_2$ reveals anisotropic and quasi-two-dimensional (2D) magnetic excitations close to \textbf{Q}$_{\texttt{AFM}}=({1}{2}/{1}{2})$ - the 2D antiferromagnetic (AFM) wave-vector of the parent BaFe$_2$As$_2$ compound. The correlation length anisotropy of these low energy fluctuations is consistent with spin nematic correlations in the $J_1$-$J_2$ model with $J_1/J_2 \sim$ 1. The spin resonance at $\sim$8.3 meV in the SC state displays the same anisotropy. The anisotropic fluctuations experimentally evolve into two distinct maxima only along the direction transverse to \textbf{Q}$_{\texttt{AFM}}$ above $\sim$80 meV indicating unusual quasi-propagating excitations.

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H. -F. Li, C. Broholm, D. Vaknin, R. M. Fernandes, D. L. Abernathy, M. B. Stone, D. K. Pratt, W. Tian, Y. Qiu, N. Ni, S. O. Diallo, J. L. Zarestky, S. L. Bud'ko, P. C. Canfield, R. J. McQueeney. 2014-07-07. Anisotropic and quasipropagating spin excitations in superconducting Ba(Fe0.926Co0.074)2As2. https://doi.org/10.1103/physrevb.82.140503

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