1. A resistive-switching memory element comprising: a first electrode adjacent to an interlayer dielectric; a spacer over at least a portion of the interlayer dielectric and over a portion of the first electrode; a first metal oxide layer over at least a portion of the first electrode such that a first interface between the metal oxide layer and the electrode is smaller than a top surface of the electrode; and a second electrode over the metal oxide, wherein the second electrode comprises a different material than the first electrode.