# Nematic and Antiferromagnetic Quantum Criticality in a Multi-Orbital Hubbard Model for Iron Pnictides

## TL;DR

This paper investigates quantum criticality in a multi-orbital Hubbard model for iron pnictides, revealing a single critical point where nematic and antiferromagnetic orders emerge simultaneously, using advanced variational Monte Carlo methods.

## Contribution

It introduces a microscopic multi-orbital model analysis with non-perturbative electron correlations, identifying a quantum critical point relevant to iron-based superconductivity.

## Key findings

- Evidence for a unique quantum critical point with coexisting nematic and antiferromagnetic orders.
- The critical point occurs in the bad-metal regime of the phase diagram.
- Implications for understanding iron-based superconductivity are discussed.

## Abstract

The extent to which quantum criticality drives the physics of iron pnictides is a central question in the field. Earlier theoretical considerations were based on an effective field theory, and the proposed realization in P-doped iron arsenides has received extensive experimental evidence. To connect the quantum critical behavior with the underlying electronic physics, it is important to analyze it within microscopic models. Here, we do so for a multi-orbital model containing both Hubbard and Hund's interactions, by a variational Monte Carlo method based on Jastrow-Slater wave functions that allow for a non-perturbative treatment of electron correlations. We find strong evidence for the existence of a unique quantum critical point, where both nematic and $(\pi,0)$ antiferromagnetic orders develop together, in the bad-metal regime of the phase diagram. Implications of our results for the iron-based superconductivity are discussed.