Publication Type
Journal
Journal Name
Physical Review Letters
Publication Date
Page Number
144306
Volume
82
Abstract
Inelastic neutron scattering from superconducting (SC) Ba(Fe0:926Co0:074)2As2 reveals anisotropic and quasi-two-dimensional (2D) magnetic excitations close to QAFM = ( 1/2 1/2 ) - the 2D antiferromagnetic wavevector of the parent BaFe2As2 compound. The correlation length anisotropy of these low energy fluctuations is consistent with spin nematic correlations in the J1-J2 model with J1=J2 1.The magnetic resonance at 8.30.1 meV in the SC state displays the same anisotropy. Above 50 meV, the anisotropic fluctuations evolve into two distinct maxima transverse to QAFM indicatingnovel quasi-propagating excitations.
