April 2011

Journal

Anisotropic and quasi-propagating spin excitations in optimally-doped superconducting Ba(Fe0.926Co0.074)2As2

By:
Li, Haifeng; Broholm, C.; Vaknin, D.; Abernathy, Douglas L; Pratt, Daniel K; Tian, W.; Fernandes, R; Qiu, Y.; Ni, N.; Stone, Matthew B; Diallo, S. O.; de la Cruz, Clarina; Zarestky, J.; Budko, S; Canfield, P.; McQueeney, R.
Journal Name:
Physical Review Letters
Page Number:
144306
Volume:
82
Issue Number:
N/A
Publication Date:
April 13, 2011

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.