High-temperature superconductivity in layered iron compounds

Basic experimental data are presented for a new class of high-temperature superconductors, layered iron compounds of the types $RE\mathrm{OFeAs}$ ($RE=\mathrm{La, Ce, Nd, Pr, Sm,}\dots$), $A\mathrm{Fe_2As_2}$ ($A=\mathrm{Ba, Sr,}\dots$), $A\mathrm{FeAs}$ ($A=\mathrm{Li},\dots$) and $\mathrm{FeSe(Te)}$. The electronic spectra of these compounds are discussed, including the effect of correlations and the spectrum and role of collective excitations (phonons and spin waves). Basic models for describing various types of magnetic ordering and Cooper pairing are reviewed.