Electronic and magnetic properties of iron pnictides and chalcogenides from first-principles calculations

Hyoung Joon Choi, Yonsei University

Electronic, and magnetic properties of various iron pnictides and chalcogenides are studied using first-principles density functional calculations and compared with experimental results[1,2,3]. It is shown that atomic structures and low-temperature magnetic orderings are well described by the density functional theory while both electronic bandwidths and Fe magnetic moments are quite overestimated in the calculations. We discuss important magnetic interactions in the materials and the role of local-moment interactions in the magnetic ordering in iron pnictides[2]. Our results indicate that the local-moment interactions are the dominant factors over the Fermi-surface nesting in determining the stability of the magnetic phase in iron pnictides and that the partial gap is an induced feature by a specific magnetic order[2]. We also present chalcogen-height dependent magnetic interactions and magnetic order switching in FeSe_xTe_1-x[3]. It is found that the stability of magnetic phases in iron chalcogenides is very sensitive to the height of chalcogen species from the Fe plane: while FeTe with optimized Te height has the double-stripe-type (π, 0) magnetic ordering, the single-stripe-type (π, π) ordering becomes the ground state phase when Te height is lowered below a critical value by, e.g., Se doping[3]. Our findings provide a comprehensive and unified view to understand the magnetism in iron pnictides and FeSe_xTe_1-x. This work was supported by National Research Foundation of Korea (KRF-2007-314-C00075 and 2009-0081204). Computational resources have been provided by KISTI Supercomputing Center (KSC-2008-S02-0004).

References

[1] C.-Y. Moon, S. Y. Park, and H. J. Choi, arXiv:0808.1348; Phys. Rev. B 78, 212507 (2008).

[2] C.-Y. Moon, S. Y. Park, and H. J. Choi, arXiv:0902.2359; Phys. Rev. B 80, 054522 (2009).

[3] C.-Y. Moon and H. J. Choi, arXiv:0909.2916 (2009); submitted.