Influence of ZnO-based Interlayer and Noble-Metal Underlayer on the Perpendicular Magnetic Properties of CoPt Films

Abstract

  This study aims to develop a new film structure wherein CoPt can exhibit higher perpendicular magnetic anisotropy with samples having a magnetic layer/intermediate layer/underlayer/seed layer/substrate with AZO(Al-doped ZnO) in the intermediate layer and noble metals, such as Ru, Au, and Ag, in the underlayer. X-ray diffraction (XRD) measurements were used to investigate the effects of crystal structure on the perpendicular magnetic properties of CoPt. CoPt with a c-axis-oriented hcp structure exhibited high perpendicular magnetic anisotropy. Introducing a stacking fault into the c-axis-oriented hcp structure changed it into a (111)-axis-oriented fcc structure, reducing the vertical magnetic anisotropy. Herein, we can measure the (110) and (100) diffraction peaks of the c-axis-oriented CoPt, i.e., D_L and D_H, using in-plane XRD. For (111) axis-oriented fcc metal, we can detect D_H but not D_L. We investigated the degree of stacking faults by obtaining I_L/I_H, which is the ratio of the peak intensity I_L and I_H of D_L and D_H, respectively. Consequently, we observed that the insertion of an intermediate AZO layer improves the crystallinity of samples containing fcc Au and Ag metal in the underlayer and decreases the crystallinity of samples containing hcp Ru metal.