Co/Pd multilayer media with Pd inorganic granular seed layer for perpendicular recording

Abstract

We have investigated the Co/Pd multilayer media with a Pd–SiN granular seed layer as perpendicular recording media. The Pd–SiN granular seed layer and the Co(0.2 nm)/Pd(0.8 nm) multilayer were formed by dc and rf sputtering at room temperature on a FeTaC soft magnetic underlayer. The Pd–SiN granular seed layer of 3 nm was very effective to get good magnetic properties with coercivity of 3.9 kOe, a nucleation field of −2.1 kOe, and a M–H slope parameter 4π(dM/dH)H=Hc of 1.4. In addition, it was found that growth of multilayer grains is sensitive to surface conditions of the soft magnetic underlayer. The average column diameter of 13.7 nm with a dispersion of 21.7% was evaluated from the plan-view transmission electron microscope image of well-separated Co/Pd columns with a boundary, which was grown on the Pd–SiN seed layer and the soft magnetic underlayer with Ar plasma etching. Atomic force microscope measurements showed that mean roughness (Ra) of the FeTaC surface decreased from 0.46 to 0.39 nm by the plasma etching. This surface treatment on the soft magnetic underlayer gave better signal to noise ratio by 1.6 dB in playback performance by using of a spin stand with a merged-type ring writer and giant magnetoresistance reader.

Microstructure of a Co/Pd multilayered perpendicular recording medium with Pd seeds prepared by electrochemical process

“…Suppression of intergranular exchange coupling is significant for improving read-write (R/W) characteristics of a Co/Pd multilayered medium with a soft magnetic underlayer (SUL). It has been reported that a deposition of ultra-thin Pd-based seedlayers, such as Pd-SiN [2], PtB/Pd/MgO [3], and Pd/Si [4], on SULs successfully reduced the intergranular exchange coupling of Co/Pd multilayered films, where these seedlayers have been conventionally deposited using a sputtering method. On the other hand, we have focused on the fabrication of the metallic seeds on the SUL using an electrochemical method.…”

Magnetic Thin Films for Perpendicular Magnetic Recording Systems

“…The intermediate layers meeting these demands have been developed by sputtering for various perpendicular magnetic recording media. For instance, in the case of the medium with Co/Pd multilayered perpendicular magnetization film [22,23], Pd-based intermediate layers such as Pd/ITO [24], Pt-B/Pd/MgO [25], Pd-Si-N [26], and Pd/Si [27][28][29] were reported to successfully improve magnetic properties of the Co/Pd multilayered films. In these intermediate layers, fine Pd grains provide the suitable nucleation site for the magnetically isolated Co/Pd crystal grains, leading to weak intergranular exchange coupling and good read and write characteristics.…”

Reduction of medium noise of co-pd multilayered perpendicular magnetic recording media by a thin carbon interlayer

“…Sayama and J. Kawaji and B-O [4], and the introduction of a thin film of materials such as indium-tin-oxide [5], Au-SiO [6], SiO [7], and Pd-SiN [8] as an underlayer, have been reported to decrease the intergranular exchange coupling. We also have reported that the introduction of an amorphous carbon or silicon underlayer to the [Co-Pd] multilayered media decreased the intergranular exchange coupling and, thereby, reduced the medium noise [9].…”