Stability of the Antiferromagnetic State in the Electron Doped Iridates

Abstract

Iridates such as Sr${}_2$IrO${}_4$ are of considerable interest owing to the formation of the Mott insulating state driven by a large spin-orbit coupling. However, in contrast to the expectation from the Nagaoka Theorem that a single doped hole or electron destroys the anti-ferromagnetic (AFM) state of the half-filled Hubbard model in the large U limit, the anti-ferromagnetism persists in the doped Iridates for a large dopant concentration beyond half-filling. With a tight-binding description of the relevant J${}_{\mathrm{eff}}$ = 1/2 states by the third-neighbor ($t_1$, $t_2$, $t_3$, $U$) Hubbard model on the square lattice, we examine the stability of the AFM state to the formation of a spin spiral state in the strong coupling limit. The third-neighbor interaction $t_3$ is important for the description of the Fermi surface of the electron doped system. A phase diagram in the parameter space is obtained for the regions of stability of the AFM state. Our results qualitatively explain the robustness of the AFM state in the electron doped iridate (such as Sr${}_{2-x}$La${}_x$IrO${}_4$), observed in many experiments, where the AFM state continues to be stable until a critical dopant concentration.

16 pages, 8 figures

References in corpus (4)

• Novel Jeff = 1/2 Mott State Induced by Relativistic Spin-Orbit Coupling in Sr2IrO4
• Unidirectional spin density wave state in metallic (Sr1-xLax)2IrO4
• Magnetic excitations in a three-orbital model for the strongly spin-orbit coupled iridates: Effect of mixing between the J=1/2 and 3/2 sectors
• Mott metal-insulator transition in the Doped Hubbard-Holstein model

Cited by in corpus (2)

• Electronic structure and optical properties of Sr${}_2$IrO${}_4$ under epitaxial strain
• Two dimensional electron gas in the $\delta$-doped iridates with strong spin-orbit coupling: La${}_{\delta }$Sr${}_2$IrO${}_4$