Defect gradient to boost nonvolatile memory performance

A nonvolatile memory element, comprising:

• a first electrode layer;
• a first variable resistance layer disposed over the first electrode layer;
• a first layer disposed on the first variable resistance layer;
• a second variable resistance layer disposed on the first layer;
• and
• a second electrode layer disposed over the second variable resistance layer,
• wherein:
• the first and second variable resistance layers each comprise a first material that comprises a first chemical element and a second chemical element;
• and
• the first layer comprises a metal that has a greater affinity for the first chemical element as compared to the first material.

A nonvolatile memory element, comprising:

• a first electrode layer;
• a first variable resistance layer disposed over the first electrode layer;
• a first layer disposed on the first variable resistance layer;
• a second variable resistance layer disposed on the first layer;
• and
• a second electrode layer disposed over the second variable resistance layer,
• wherein:
• the first variable resistance layer, the second variable resistance layer and the first layer each comprise a first chemical element and a second chemical element;
• and
• the stoichiometry of the first and second chemical elements in the first and the second variable resistance layers is different than the stoichiometry of the first and second chemical elements in the first layer.

A nonvolatile memory element, comprising:

• a first electrode layer;
• a first variable resistance layer disposed over the first electrode layer;
• a first layer disposed on the first variable resistance layer;
• a second variable resistance layer disposed on the first layer;
• a second electrode layer disposed over the second variable resistance layer;
• and
• a second layer,
• wherein the second variable resistance layer is disposed between the first layer and second layer, and the first and second layers each comprise a metal selected from the group consisting of titanium, aluminum, and combinations thereof.

A nonvolatile memory element, comprising:

• a first electrode layer;
• a first variable resistance layer disposed over the first electrode layer;
• a first layer disposed on the first variable resistance layer;
• a second variable resistance layer disposed on the first layer;
• a second electrode layer disposed over the second variable resistance layer;
• and
• a second layer that is disposed on the second variable resistance layer, wherein the first layer and the second layer each have a thickness that is substantially equal.