Development of magnetization reversal technique at low power consumption using a stress-induced magnetic anisotropy for perpendicular MRAM

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Thin films with perpendicular magnetic anisotropy have a potential to achieve high-density cell arrangements as a perpendicular magnetic random access memory (p-MRAM). We have demonstrated a new method to reduce perpendicular coercivity of DyFeCo films using a stress-induced magnetic anisotropy. An isotropic stress applied to in-plane direction of the film was so effective to cause reduction of perpendicular magnetic anisotropy during the writing process if the film has large magnetostriction constant. In this study, we have succeeded to cause magnetization reversal at low magnetic field as low as 1/6 of original coercivity of the film. Magnetization processes of the films were measured using anomalous Hall effects and in-plane stress to the films was induced by a mechanical indentation method. It is observed that about 500 Oe of magnetic field in the reverse direction is enough to reverse completely the magnetization of the film which has an original coercivity of 3.3 kOe if the in-plane stress is applied to the film. This technique is applicable to the writing process of p-MRAM with wide writing margin at low power consumption.