We have found a novel method for increasing the giant magnetoresistance (GMR) of Co/Cu spin valves with the use of oxygen. Surprisingly, spin valves with the largest GMR are not produced in the best vacuum. Introducing 5x10-9 Torr (7x10-7 Pa) into our ultrahigh vacuum deposition chamber during spin-valve growth increases the GMR, decreases the ferromagnetic coupling between magnetic layers, and decreases the sheet resistance of the spin valves. It appears that the oxygen may act as a surfactant during film growth to suppress defects and to crate a surface which scatters electrons morespecularly. Using this technique, bottom spin valves and symmetric spin valves with GMR values of 19% and 24.8%, respectively, have been produced. These are the largest values ever reported for such structures.
Citation: Journal of Applied Physics
Pub Type: Journals
Giant Magnetoresistance(GMR), magnetic layers, spin valves, surfactant