Revealing pressure-driven self-doping of polarons in magnetite

Magnetite (Fe3O4) is one of the most fascinating quantum materials exhibiting the enigmatic first-order Verwey transition. This transition manifests itself in an abrupt change in electrical conductivity and in the nature of the trimeron correlations (linear three-Fe-site units) from long- to short-range. We recently discovered that heating Fe3O4 above ~400 K results in a cation reordering and consequently a hole self-doping effect which alters short-range correlations at the octahedral sublattice. Strikingly, four regimes of self-doping can be identified that map the temperature depenendence electrical conductivity and magnetism up to the Curie temperature providing an elegant descriptor of correlations. Here we propose to investigate the effect of pressure on cation ordering and short-range correlations in Fe3O4 using Fe Kedge HERFD-XAS in search of a pressure-driven self-doping effect.