The role of structural disorder on the electronic nematicity of iron-based superconductors*

Electronic nematicity is a key ingredient for the unconventional superconductivity observed in iron-based superconductors. Thus, elucidating its evolution in the phase diagram is crucial for a complete understanding of these materials. Regardless of the microscopic mechanism at play, the electronic nematic instability always triggers a structural tetragonal-to-orthorhombic phase transition, reflecting the fact that shear strain acts as a conjugate nematic field. An important consequence of this nemato-elastic coupling is that any type of lattice disorder, such as dislocations and vacancies, will strongly affect the nematic phase by introducing local strains. While it is common to model them as random uncorrelated nematic fields, the distribution of local strains in a crystal is correlated and anisotropic. Additionally, since the nematic order is a vestige of the stripe-magnetic order, structural disorder creates non-trivial correlations between these two intertwined degrees of freedom. In this talk, we use Monte Carlo simulations to investigate models that capture these effects, going beyond a description in terms of the random-field Ising model. We discuss experimental manifestations of these effects and their impact on the nematic phase of iron-based superconductors.