Three-dimensional Stacking of Canted Antiferromagnetism and Pseudospin Current in Undoped Sr${}_2$IrO${}_4$: Symmetry Analysis and Microscopic Model Realization

Abstract

Recent optical second-harmonic generation experiments observed unexpected broken spatial symmetries in the undoped spin-orbit Mott insulator Sr${}_2$IrO${}_4$, leading to intensive debates on the nature of its ground state. We propose that it is a canted antiferromagnetism with a hidden order of circulating staggered pseudospin current. Symmetry analysis shows that a proper $c$-axis stacking of the canted antiferromagnetism and the pseudospin current lead to a magnetoelectric coexistence state that breaks the two-fold rotation, inversion, and time-reversal symmetries, consistent with experimental observations. We construct a three-dimensional Hubbard model with spin-orbit coupling for the five localized 5$d$ Wannier orbitals centered at Ir sites, and demonstrate the microscopic realization of the desired coexistence state in a wide range of band parameters via a combination of self-consistent Hartree-Fock and variational calculations.

10 pages, 5 figures

References in corpus (19)

• Novel Jeff = 1/2 Mott State Induced by Relativistic Spin-Orbit Coupling in Sr2IrO4
• Models and Materials for Generalized Kitaev Magnetism
• Twisted Hubbard Model for Sr2IrO4: Magnetism and Possible High Temperature Superconductivity
• Fermi Arcs in a Doped Pseudospin-1/2 Heisenberg Antiferromagnet
• Monte Carlo study of an unconventional superconducting phase in Ir-oxide J_{eff}=1/2 Mott insulators induced by carrier doping
• The magnetic and crystal structures of Sr2IrO4: A neutron diffraction study
• Odd-parity triplet superconductivity in multi-orbital materials with strong spin-orbit coupling: applications to doped Sr2IrO4
• Robustness of basal-plane antiferromagnetic order and the $J_{eff}=1/2$ state in single-layer iridate spin-orbit Mott insulators
• Spin-orbit tuned metal-insulator transitions in single-crystal Sr2Ir1-xRhxO4 (0\leqx\leq1)
• Neutron scattering study of correlated phase behavior in Sr2IrO4
• Square Lattice Iridates
• Electronic structures of layered perovskite Sr2MO4 (M=Ru, Rh, and Ir)
• A structural distortion induced magneto-elastic locking in Sr${}_2$IrO${}_4$ revealed through nonlinear optical harmonic generation
• Unidirectional spin density wave state in metallic (Sr1-xLax)2IrO4
• Model analysis of magnetic susceptibility of Sr${}_2$IrO${}_4$ - 2D $J_{\mathrm{eff}}$ = 1/2 Heisenberg system with competing interlayer couplings
• Charge partitioning and anomalous hole doping in Rh-doped Sr2IrO4
• Spin-orbit-enhanced magnetic surface second-harmonic generation in Sr${}_2$IrO${}_4$
• Nonsymmorphic Dirac semimetal and carrier dynamics in doped spin-orbit-coupled Mott insulator Sr${}_2$IrO${}_4$
• Low-energy electrodynamics of Dirac semimetal phases in the doped Mott insulator Sr${}_2$IrO${}_4$