Sputter synthesis of modulated multilayer high-energy-product permanent magnet films

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Abstract
Multilayered permanent magnet films with alternating layers differing vastly in anisotropy field and intrinsic coercivity have been sputter synthesized from Sm‐Co‐based TDK‐type 2‐17 bulk targets. The basic layer thickness range for which modulated properties can be observed has been investigated from <0.1 to ≳10 μm. The individual layers have been synthesized so as to exhibit high‐static‐energy product values of ≊15 MGOe. The alternating layers exhibited coercivities around 5 and 15 kOe, respectively, so that for applied reversed fields in the vicinity of 10 kOe the alternating layers have their in‐plane magnetizations pointing in opposite directions, reducing the net magnetization to near zero. The magnetic property modulation was accomplished through modulation of the Sm content through sputter process control and the method of crystallization of the alternating layers, without changing either the sputtering targets or substrate positions. For such modulated layer films, the system magnetic energy density in the absence of external fields is a function of the reversed‐field value applied after initial in plane saturation.