Programmable metallization memory cells that have an inert electrode and an active electrode positioned in a non-overlapping manner in relation to a substrate. A fast ion conductor material is in electrical contact with and extends from the inert electrode to the active electrode, the fast ion conductor including superionic clusters extending from the inert electrode to the active electrode. A metal layer extends from the inert electrode to the active electrode, yet is electrically insulated from each of the inert electrode and the active electrode by the fast ion conductor material. Methods for forming programmable metallization cells are also disclosed.