NiCo films with perpendicular magnetization anisotropy deposited on dielectric substrate by using polyol process

Abstract

In this paper, the polyol process, a catalyst free, non-aqueous, and electroless process, is developed to deposit the nanostructured Ni xCo 100 − x magnetic films on aluminum nitride (AlN) substrate. Nickel (II) acetate tetrahydrate and cobalt (II) acetate tetrahydrate were reduced by ethylene glycol (EG) at 180 °C, and the reduced Ni and Co nanostructures were deposited on the AlN substrate merged in boiling EG for 60 min. The elongated nanostructures in the films are detected through the scanning electron microscopy (SEM). Interestingly, some of the elongated nanostructures are pointing out of the substrate. It indicates that the component ratio of Ni and Co in the films is different with the starting precursor molar ratio. The film thickness increases from 1 to 1.8 μm when the atomic ratio of Co (at.%) in the film increased from 44.6% to 70.8%. Furthermore, it is found that the crystallite size decreases from 44 to 25 nm with increasing Ni (at.%). In addition, the magnetic properties have been analyzed through vibrating sample magnetometer (VSM) at room temperature. The results show that the films have the perpendicular preferred anisotropy. The anisotropy field (H K) for the Ni 50Co 50 is about 4.75 kOe, which is possibly caused by the assembled direction of the elongated nanostructures.