1. A nonvolatile memory device, comprising: at least one switching device; and at least one storage node electrically connected to the at least one switching device; wherein the at least one storage node comprises: a lower electrode; one or more oxygen-deficient metal oxide layers; one or more data storage layers; and an upper electrode; wherein at least one of the one or more metal oxide layers is electrically connected to the lower electrode, wherein at least one of the one or more data storage layers is electrically connected to at least one of the one or more metal oxide layers, and wherein the upper electrode is electrically connected to at least one of the one or more data storage layers.