Abstract
Motivated by recent neutron scattering experiments, we study the ordering of spins in the iron-based superconductors , assuming them in proximity to a Mott insulator in the phase diagram. The ground state of the parent system with is a spin-density wave with ordering wave vector or . Upon raising the temperature, we find that the system restores SU(2) symmetry, while an Ising symmetry remains broken, explaining the experimentally observed lattice distortion to a monoclinic crystal structure. Upon further temperature increase, the spins finally disorder at a second transition. The phase transition driven by doping with charge carriers similarly splits into an transition and an Ising transition with at larger doping.
- Received 7 May 2008
DOI:https://doi.org/10.1103/PhysRevB.78.020501
©2008 American Physical Society