How interactions alter the number of electrons in iron-based superconductors

In 2008, a new family of superconductors was discovered, based on square planar iron. This attracted the attention of many physicists because superconductivity was found to occur up to relatively high temperatures (56K), which was very unexpected from a theoretical point of view. The LPS, CEA-SPEC and CASSIOPEE research groups have used angle-resolved photoemission spectroscopy to study these solids for 5 years. Recently, they have shown evidence of shifts in the electron bands of one family of these superconductors, which modify the number of electrons present, depending on the temperature.