Iron-based superconductors

Iron-based superconductors (FeSC) are iron-containing chemical compounds whose superconducting properties were discovered in 2006^[1]

Classes/composition

Pnictides (FeAs, ...)

contain chemical elements in group 15 of the periodic table, here typically arsenic (As) and phosphorus (P)

Oxypnictides (LaOFeAs, ...) often referred to as the '1111' pnictides.

Chalcogenides (FeSe, ...)

Structure

• Layered
• Most of the correlated physics (superconductivity, magnetism) occurs in the Fe(Pn or Ch) layers
• Fe atoms form approximately square lattice

Phase diagram

• Parent (undoped compound) is typically a spin density wave, sometimes nematic at low temperature
• superconductivity has transition temperatures up to mid 50K
• Phases can be tuned by composition, pressure, strain, and in the case of thin films by substrate (strain, electron phonon coupling)
• superconductivity exists both for electron and hole doping
  • for review see https://arxiv.org/pdf/1604.03566.pdf

Electronic properties

• Can have one or more types of Fermi surfaces
• Fe atoms carry local magnetic moments in the magnetic (SDW) phases
• Electronic correlations are believed to be weaker than in the case of cuprates ^[2] -- band and mean-field theory may work better

References

1. Kamihara, Yoichi; Hiramatsu, Hidenori; Hirano, Masahiro; Kawamura, Ryuto; Yanagi, Hiroshi; Kamiya, Toshio; Hosono, Hideo (2006). "Iron-Based Layered Superconductor: LaOFeP". J. Am. Chem. Soc. 128 (31): 10012–10013
2. M. M. Qazilbash, J. J. Hamlin, R. E. Baumbach, Lijun Zhang, D. J. Singh, M. B. Maple & D. N. Basov, "Electronic correlations in the iron pnictides", Nature Physics volume 5, pages 647–650 (2009)