Nematic State of the Pnictides Stabilized by the Interplay Between Spin, Orbital, and Lattice Degrees of Freedom

TL;DR

This study investigates the nematic state in iron-based superconductors using a three-orbital spin-fermion model with lattice interactions, revealing the necessity of spin-lattice and orbital-lattice couplings for experimental consistency.

Contribution

It demonstrates that both spin-lattice and orbital-lattice couplings are essential to stabilize nematic order and reproduce experimental observations in a three-orbital model.

Findings

Both couplings are needed to stabilize nematic order.

The interplay controls the separation of transition temperatures.

Simulations match experimental resistivity and ARPES data.

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, {\it both} the spin-lattice and orbital-lattice couplings are needed. The interplay between their respective coupling strengths regulates the separation between the structural and N\'eel transition temperatures. Experimental results for the temperature dependence of the resistivity anisotropy and the angle-resolved photoemission (ARPES) orbital spectral weight are reproduced by the present numerical simulations.