The fundamental effects of adding several elements to the Co‐Cr system on the properties of Co‐Cr‐based films were extensively investigated. Tantalum, molybdenum, vanadium, and rhenium were chosen as the additives. A large amount of each element was added to a Co–17‐at. Cr film. Ta addition improved the squareness and suppressed the in‐plane coercive force without lowering the perpendicular coercive force for the films with perpendicular magnetization. All the additives were effective in suppressing the grain growth. The ternary alloy films were likely to have finer grains than Co‐Cr films. Ta was found to be the most advantageous in a wide range of the content, from the total balance of squareness, coercive force, and grain size. The recording characteristics of Co‐Cr‐Ta films were also examined in comparison with those of Co‐Cr films. The recording density and the signal‐to‐noise ratio of Co‐Cr‐Ta films were appreciably higher than those of Co‐Cr films.
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