Coexistence of Competing Antiferromagnetic and Superconducting Phases in the Underdoped Ba(Fe0.953Co0.047)2As2 Compound Using X-ray and Neutron Scattering Techniques

Neutron and x-ray diffraction studies show that the simultaneous first-order transition to an orthorhombic and antiferromagnetic (AFM) ordered state in BaFe2As2 splits into two transitions with Co doping. For Ba(Fe0.953Co0.047)(2)As-2, a tetragonal-orthorhombic transition occurs at T-S=60 K, followed by a second-order transition to AFM order at T-N=47 K. Superconductivity occurs in the orthorhombic state below T-C=17 K and coexists with AFM. Below T-C, the static Fe moment is reduced along with a redistribution of low energy magnetic excitations indicating competition between coexisting superconductivity and AFM order.