Regular Article

Quantum Monte Carlo study of the S₄ symmetric microscopic model for iron-based superconductors

¹ Beijing Computational Science Research Center, Beijing 100084, P.R. China
² Department of Physics, Beijing Normal University, Beijing 100875, P.R. China
³ Faculty of Physics and Electronic Technology, Hubei University, Wuhan 430062, P.R. China

^a e-mail: gkliu@mail.bnu.edu.cn

Received: 24 July 2018
Received in final form: 14 January 2019
Published online: 18 February 2019

Abstract

The S₄ symmetric microscopic model with two iso-spin components has been studied via constrained-path quantum Monte Carlo simulation. Our results demonstrate a stable (π, 0) or (0, π) magnetic order which is significantly enhanced on increasing both the Coulomb repulsion U and Hund’s coupling strength J. Also, our simulation indicates that the magnetic order tends to be in an orthomagnetic state, in which the nearest-neighbour magnetic moment are orthogonal to each other, rather than in a collinear antiferromagnetic order. Interestingly, when the system is doped away from half filling, the magnetic order is obviously elevated in the low doping density, and then significantly suppressed when more electrons are introduced. Meanwhile, we find that an A_1g s_±-wave pairing dominates all the singlet nearest-neighbour pairings, and is significantly enhanced by electron doping.