1. A memristive device comprising: a first electrode; a second electrode; a memristive matrix interposed between said first electrode and said second electrode; a porous dopant diffusion element in physical contact with said memristive matrix and in proximity to at least one of said first electrode and said second electrode; and a first mobile dopant species, said first mobile dopant species moving through said porous dopant diffusion element in response to a programming electrical field generated by said first electrode and said second electrode, said programming electrical field altering a distribution of said first mobile dopant species within said memristive matrix.