Transition from three-dimensional anisotropic spin excitations to two-dimensional spin excitations by electron doping the FeAs-based BaFe1.96Ni0.04As2 superconductor.
We use neutron scattering to study the effect of electron doping on the structural or magnetic order in BaFe2As2. In the undoped state, BaFe2As2 exhibits simultaneous structural and magnetic phase transitions below 143 K. Upon electron doping to form BaFe1.96Ni0.04As2, the system first displays the lattice distortion near approximately 97 K, and then orders antiferromagnetically at 91 K before developing weak superconductivity below approximately 15 K. The effect of electron doping is to reduce the c-axis exchange coupling in BaFe2As2 and induce quasi-two-dimensional (2D) spin excitations. These results suggest that the transition from 3D spin waves to quasi-2D spin excitations by electron doping is important for the separated structural and magnetic phase transitions in iron arsenides.
Department of Physics and Astronomy, The University of Tennessee, Knoxville, Tennessee 37996-1200, USA.
Leland W
LW
Harriger
Astrid
A
Schneidewind
Shiliang
S
Li
Jun
J
Zhao
Zhengcai
Z
Li
Wei
W
Lu
Xiaoli
X
Dong
Fang
F
Zhou
Zhongxian
Z
Zhao
Jiangping
J
Hu
Pengcheng
P
Dai