Direct evidence of phase separation in as-deposited Fe(Co)-Ag films with giant magnetoresistance

High-resolution analytical electron microscopy (EM) on as-deposited dilute Fe(Co)-Ag films showed Fe(Co) clusters embedded in a Ag matrix suggesting that these materials are not uniform substitutional alloys as it was previously believed. The cluster sizes observed from the EM images are slightly larger than those calculated from magnetization curves, and this has been attributed to the interface roughness existing between the magnetic clusters and the nonmagnetic matrix. The magnetic properties and magnetoresistance values in these films are also discussed relative to the high-resolution electron-microscopy results.