Abstract
The nematic state of the iron-based superconductors is studied in the undoped limit of the three-orbital
(xz, yz, xy) spin-fermion model via the introduction of lattice degrees of freedom. Monte Carlo
simulations show that in order to stabilize the experimentally observed lattice distortion and nematic
order, and to reproduce photoemission experiments, both the spin-lattice and orbital-lattice couplings are
needed. The interplay between their respective coupling strengths regulates the separation between the
structural and Ne´el transition temperatures. Experimental results for the temperature dependence of the
resistivity anisotropy and the angle-resolved photoemission orbital spectral weight are reproduced by
the present numerical simulations.
