Abstract
The magnetic phase diagrams of models for quasi-one-dimensional compounds belonging to the iron-based-superconductor family are presented. The five-orbital Hubbard model and the real-space Hartree–Fock approximation are employed, supplemented by density functional theory to obtain the hopping amplitudes. Phase diagrams are constructed by varying the Hubbard and Hund couplings at zero temperature. The study is carried out at electronic density (electrons per iron) , which is of relevance for the already-known material , and also at , where representative compounds still need to be synthesized. At there is a clear dominance of staggered spin order along the chain direction. At and with the realistic Hund coupling , the phase diagram is far richer, including a variety of “block” states involving ferromagnetic clusters that are antiferromagnetically coupled, in qualitative agreement with recent density matrix renormalization group calculations for the three-orbital Hubbard model in a different context. These block states arise from the competition between ferromagnetic order (induced by double exchange and prevailing at large ) and antiferromagnetic order (dominating at small ). The density of states and orbital compositions of the many phases are also provided.
4 More- Received 30 March 2014
- Revised 9 June 2014
DOI:https://doi.org/10.1103/PhysRevB.90.035128
©2014 American Physical Society