Collective Modes and Emergent SO(6) Symmetry in the Iron Pnictides

We show the existence of an emergent SO(6) symmetry in the low energy description of the iron pnictides. This approximate symmetry provides a unifying framework for the occurrence of spin density wave (SDW) and superconductivity (SC) in these materials. We use this symmetry to make several predictions for future experiments, including the topology of the phase diagram and the presence of various resonant modes in neutron scattering experiments in both the SC and SDW phases. We also predict the existence of a new “Orbital Density Wave” state, which competes with both SDW and SC orders.

Daniel Podolsky,1, 2 Hae-Young Kee,1 and Yong Baek Kim1
1Department of Physics, University of Toronto, Toronto, Ontario M5S 1A7, Canada
2Physics Department, Technion, Haifa 32000, Israel