Electride-like properties of infinite-layer nickelates

Oxide based electrides are materials in which topotactic removal of loosely bound oxygens leaves behind voids with a landscape of attractive potentials for electrons. We find that this is also what happens in the recently discovered infinite-layer nickelates where one of the two extra electrons needed for charge neutrality when the apical oxygen is removed from the cubic perovskite precursor compound is to a large degree located in the oxygen vacancy position rather than both mainly used to convert Ni from 3+ to 1+. This is shown to be the main reason for the theoretical difficulty in determining the much debated elusive Fermi surface of these novel superconductors.