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arXiv · 0804.4293

Ising and Spin orders in Iron-based Superconductors

Cenke Xu·Markus Mueller·Subir Sachdev
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Abstract

Motivated by recent neutron scattering experiments, we study the ordering of spins in the iron-based superconductors La(O_{1-x}F_x)FeAs, assuming them in proximity to a Mott insulator in the phase diagram. The ground state of the parent system with x = 0 is a spin density wave with ordering wave vector Q = (0, π) or (π, 0). Upon raising the temperature, we find the system to restore 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 O(3) transition, and an Ising transition with z = 3 at larger doping.

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Cenke Xu, Markus Mueller, Subir Sachdev. 2008-11-19. Ising and Spin orders in Iron-based Superconductors. https://doi.org/10.1103/physrevb.78.020501

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