Theoretical studies of a three-band Hubbard model with a strong spin-orbit coupling for 5d transition metal oxide Sr2IrO4

24th IUPAP Conference on Computational Physics

物理学;计算机科学

Shirakawa, Tomonori^1,2,3 ; Watanabe, Hiroshi^1,2,3 ; Yunoki, Seiji^1,2,3

Computational Materials Science Research Team, RIKEN AICS, Kobe, Hyogo 650-0047, Japan^1

Computational Condensed Matter Physics Laboratory, RIKEN ASI, Saitama 351-0198, Japan^2

CREST, Japan Science and Technology (JST), Kawaguchi, Saitama 332-0012, Japan^3

关键词: Antiferromagnetic exchange interactions;    Cluster approximation;    Effective Heisenberg model;    Exact diagonalization;    Ground state properties;    Long-range-ordered state;    Low-energy excitations;    Quantitative agreement;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/454/1/012068/pdf
DOI  :  10.1088/1742-6596/454/1/012068

学科分类：计算机科学（综合）

来源: IOP

【 摘 要 】

Motivated by recent experiments on Sr2IrO4, we study the ground state properties of a two-dimensional three-band Hubbard model with a strong relativistic spin-orbit coupling. Using the exact diagonalization technique, the dynamical magnetic structure factor M(q, ω) is calculated to examine the low-energy magnetic excitations. We find that the low-energy excitations in M(q, ω) are well described by an effective Heisenberg model composed of a local Kramers doublet of an effective total angular momentum Jeff| - | = 1/2. The antiferromagnetic exchange interaction estimated from M(q, ω) is as large as ∼ 80 meV, which is in good quantitative agreement with experiments. To study a possible long-range ordered state in the thermodynamic limit, we use the variational cluster approximation based on the self-energy functional theory, which is parallelized to accelerate the calculations. We find the ground state where the local Kramers doublet is in-plane antiferromagnetic ally ordered.