2011/04/30 by Rong Yu, Pallab Goswami, Qimiao Si · 1 citation
Materials Science · Physics and Astronomy · #Algorithm #Computer science #Crystal Structures and Properties #Iron-based superconductors research #Phase (matter) #Phase diagram #Physics #Rare-earth and actinide compounds #cond-mat.str-el #cond-mat.supr-con
paper · pdf · doi:10.1103/physrevb.84.094451
published as Phys. Rev. B 84, 094451 (2011) · 9 pages, 8 figures, 3 tables
openalex publication_date 2011/09/28 · arxiv created 2011/09/29 · arxiv updated 2015/03/18 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
Motivated by the experimentally observed √(5)\ifmmode×\else\texttimes\fi√(5) iron vacancy order and a block-spin antiferromagnetic phase with large magnetic moment in K0.8Fe1.6Se2, we study the magnetic phase diagram of an extended J1\ensuremath-J2 model on a (1)/(5)-depleted square lattice with √(5)\ifmmode×\else\texttimes\fi√(5) vacancy order, using a classical Monte Carlo analysis. The magnetic phase diagram involves various antiferromagnetically ordered phases, and most of them have higher-order commensuration. We find that the experimentally relevant block-spin state occupies a significant portion of the phase diagram, and we discuss the spin dynamics of this phase using a linear spin-wave analysis. By comparing the calculated magnetization with the experimental values of magnetic moment, we determine the physical parameter regimes corresponding to the block-spin antiferromagnetic phase. Based on our spin-wave calculations in different parameter regimes, we show how spin-wave degeneracy along the high-symmetry directions of the magnetic Brillouin zone can provide information regarding the underlying exchange couplings. We have also analyzed the magnetic phase diagram of a J1\ensuremath-J2 model on two different modulated square lattices relevant to KyFe1.5Se2, which respectively exhibit (1)/(4)-depleted 2\ifmmode×\else\texttimes\fi2 and 4\ifmmode×\else\texttimes\fi2 vacancy ordering.