Low resistance MgO capping layer for perpendicularly magnetized magnetic tunnel junctions

A device comprising:

• a free layer;
• a plurality of metal oxide islands disposed directly on a top surface of the free layer, and wherein the plurality of metal oxide islands includes a first metal oxide island having a first shape and a second metal oxide island spaced apart from the first metal oxide island and having a second shape that is different from the first shape;
• and
• a non-magnetic hard mask layer disposed directly on the plurality of metal oxides islands and extending between the first metal oxide island and the second metal oxide island to the top surface of the free layer such that the non-magnetic hard mask layer physically contacts the top surface of the free layer positioned between the first and second metal oxide islands.

A device comprising:

• a free layer;
• a cap layer including a first surface physically contacting the free layer, the cap layer including a second surface that opposes the first surface and a first outermost sidewall surface and an opposing second outermost sidewall surface, wherein the first outermost sidewall surface and the opposing second outermost sidewall surface extend from the first surface to the second surface of the cap layer, the cap layer further including:
• a center portion that is formed of a first metal oxide layer having a first oxidation state, the first metal oxide layer including a metal or metal alloy;
• and
• a first outer portion having a second oxidation state that extends from the first outermost sidewall surface of the cap layer to the center portion, the second oxidation state being different than the first oxidation state.