Inelastic neutron scattering from superconducting (SC) Ba (Fe 0.926 Co0.074)2 As2 reveals anisotropic and quasi-two-dimensional (2D) magnetic excitations close to Q AFM = (1 2 1 2) - the 2D antiferromagnetic (AFM) wave vector of the parent BaFe2 As2 compound. The correlation length anisotropy of these low-energy fluctuations is consistent with spin nematic correlations in the J1-J2 model with J1/J 2 ∼1. The spin resonance at ∼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 QAFM above ∼80 meV indicating unusual quasipropagating excitations.
|Original language||English (US)|
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|State||Published - Oct 12 2010|