Pencheng Dai (University of Tennessee at Knoxville / ORNL)
In this Talk, I describe the most recent progress in the field of iron-based superconductors. Using neutron scattering as a probe, we study the spin wave excitations in BaFe2As2 and RbFe1.6Se2, and its electron/hole doping evolution of the spin excitations. We find that the effective next nearest neighbor (NNN) exchange interactions for different families of materials are rather similar, thus demonstrating that the common features for superconductivity is associated with the NNN exchange interactions in these materials. These results suggest that spin excitations are the most promising candidate for electron pairing and superconductivity in iron-based superconductors, regardless of their original antiferromagnetic ordering status and electronic structure.