Spin dynamics in electron and hole-doped iron pnictide superconductors

Pengcheng Dai

The University of Tennessee

Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China


    High-temperature superconductivity in the iron-based materials emerges from, or sometimes coexists with, their metallic or insulating parent compound states. This is surprising since these undoped states display dramatically different antiferromagnetic (AF) spin arrangements and Neel temperatures. Although there is general consensus that magnetic interactions are important for superconductivity, much is still unknown concerning the microscopic origin of the magnetic states.  In this talk, progress in this area is summarized, focusing on the evolution of spin dynamics in iron pnictides and discussing their microscopic implications. It is concluded that the parent compounds are in a state that is more complex than implied by a simple Fermi surface nesting scenario, and a dual description including both itinerant and localized degrees of freedom is needed to properly describe these fascinating materials.