A single resistive memory device comprises a first metal oxide layer and a second metal oxide layer. The second metal oxide layer is located underneath the first metal oxide layer, and has a different stoichiometry than the second metal oxide layer. In embodiment, the first and second metal oxide layers each comprise different oxides of the same base metal, and the base metal may comprise tantalum. An article of manufacture comprising a single resistive memory device that is operable in a complementary resistive switching mode is also provided.