Abstract
Using Monte Carlo simulations with a tunable uniaxial strain, the nematic susceptibility of the spin fermion
model for the pnictides is calculated. The results are in excellent agreement with the experiments by Chu et al. [Science 337, 710 (2012)]. Via a Ginzburg-Landau analysis, our study suggests a nematicity in the spin fermion model primarily originating in magnetism, but with the lattice/orbital also playing a key role by boosting up critical temperatures and separating the structural TS and N´eel TN transitions. AtT >TS , Curie-Weiss behavior is observed with a characteristic temperature T ∗ being the TN of the purely electronic system. In this temperature regime, short-range magnetic order with wave vectors (π,0)-(0,π) induce local nematic fluctuations and a density-of-states pseudogap, compatible with several experiments. The present analysis relies on the study of a particular model for the iron superconductors; thus further studies are needed to conclusively establish the driver of nematicity in real materials.
