2011/10/31 by C. Liu, Chen Liu, Dao‐Xin Yao +3
Materials Science · Physics and Astronomy · #Iron-based superconductors research #Physics of Superconductivity and Magnetism #Rare-earth and actinide compounds #cond-mat.str-el #cond-mat.supr-con
paper · pdf · doi:10.1103/physrevb.85.094410
published as Phys. Rev. B 85, 094410 (2012) · 8 pages, 7 figures. v2: significantly expanded
arxiv created 2012/02/23 · openalex publication_date 2012/03/07 · arxiv updated 2012/03/09 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We study a two-orbital spin model to describe (\ensuremathπ,0) stripe antiferromagnetism in the iron pnictides. The ``double-spin'' model has an on-site Hunds's coupling and intersite interactions extending to second neighbors (inter- and intraorbital) on the square lattice. Using a variational method based on a cluster decomposition, we optimize wave functions with up to eight cluster sites (up to 216 variational parameters). We focus on the anomalously small ordered moments in the stripe state of the pnictides. To account for it, and large variations among different compounds, we show that the second-neighbor cross-orbital exchange constant should be ferromagnetic, which leads to ``partially hidden'' stripe order, with a moment that can be varied over a large range by small changes in the coupling constants. In a different parameter region, we confirm the existence of a canted state previously found in spin-wave theory. We also identify several other phases of the model.