of FeSe, where a critical temperature in excess of 100 K was reported in 2014.

Since the original discoveries several families of iron-based superconductors have emerged:
* LnFeAs(O,F) or LnFeAsO_1-x (Ln=lanthanide) with _c up to 56 K, referred to as 1111 materials. A fluoride variant of these materials was subsequently found with similar _c values.
* (Ba,K)Fe₂As₂ and related materials with pairs of iron-arsenide layers, referred to as 122