Makoto Iijima

Giant magnetoresistance properties in multilayered Co‐Ag/Cu granular alloys

In this article, we introduce a novel Co‐rich Co‐Ag/Cu granular alloy structure with increased magnetic sensitivity, and report on our study of the relationship of giant magnetoresistance (GMR) and magnetic properties to annealing temperature and Cu thickness in sputtered Co66‐Ag34/Cu multilayered films. We heat treated Co‐Ag/Cu films with Cu spacer thickness ranging from 15 to 50 A up to 500 °C, and found that the MR ratio loosely depends on both the Cu spacer thickness and the annealing temperature, peaking at 7.6% with a 25 A Cu layer and an annealing temperature of 280 °C. Based on the magnetic properties we observed, as well as x‐ray studies, we found that Cu spacers at least 25 A thick are able to separate the Co‐Ag magnetic layers. Our data also indicated that the annealing treatment changed the coupling of magnetic layers from ferromagnetic to antiferromagnetic. The high thermal stability and the high magnetic sensitivity suggest potential use of our novel multilayered structure in applications as...