Quantum Phase Transitions in a Multi-Orbital Hubbard Model for Iron Pnictides*

Quantum criticality in iron pnictides was proposed within an effective field theory that contains both antiferromgnetic and nematic order parameters [1,2]. Its proposed realization in P-doped BaFe2As2 has received extensive experimental evidence [3,4]. Here we study this problem within a multi-orbital Hubbard model containing both the Hubbard and Hund’s interactions. We analyze the effect of electron correlations in a non-perturbative way, through a variational Monte Carlo method that is based on a Jastrow-Slater wave function. We study the evolution of the electronic orders as the interaction strength is varied, report evidence for concurrent antiferromagnetic and nematic quantum critical points, and discuss the implications for superconducting pairing.

[1] J. Dai, Q. Si, J.-X. Zhu, and E. Abrahams, PNAS 106, 4118 (2009).
[2] J. Wu, Q. Si, and E. Abrahams, Phys. Rev. B 93, 104515 (2016).
[3] T. Shibauchi et al., Ann. Rev. Conden. Matter Phys. 5, 113 (2014).
[4] I. M. Hayes et al., Nature Phys. 12, 916 (2016).