Effect of Write Head Movement On Magnetic Spin Domain Reversal of Nanocube Co/Pd Alloy Material Using Micromagnetic Simulation

An analysis of the effect of the write head movement on the reversal time of the domain spin with magnetic Co/Pd on the magnetic recording layer has been carried out through micromagnetic simulation. The magnetic recording layer is modeled in the form of cubes (nanocubes) which consists of 5 domain spin. The write head, which is a transduser, moves along the domain spin to write data in the form of magnetic spins, which represent the bits on the magnetic recorder perpendicular. The results of this simulation are a profile of changes in the total magnetic field and reversal time of the domain spin when writing magnetic data for 6 nanoseconds. The calculation used in this study is an analytical calculation regarding the reversal time of the magnetic domain spin of the Co/Pd alloy material. The formulation for calculating the reversal time of domain-spin magnetization is a combination of graphical analysis and analytical calculations with visualization of the magnetic spin configuration that consisting of 5 domains spin. This simulation was carried out using the finite element method and obtained a saturation 5 field value of the magnetic alloy Co/Pd (Hs) material of 2.5 x 105 A/m and a write head (Hwh) field that 6 must be applied to the magnetic recording layer in order to reverse the uniform domain spin is 7.3 x 106 A/m. Each size of the domain spin requires a different write head, the smaller the nanocube size, the greater the write head field applied to the magnetic recording layer. Meanwhile, the effective write head 6 field amplitude that is suitable for the 20 nm domain spin is 8.3 x 106 A/m. A significant change in the total field occurs when the domain spin reverses 3 times in the first domain spin (n1), the third domain spin (n3) and the fifth domain spin (n5). The total field value when t=0.42 ns ( first domain spin reversal) is 73.69376 A/m, then the total field at t=0.42 ns (third domain spin reversal) is 3443.197 A/m and the current total field t=0.42 ns (fifth domain spin reversal) of 5480.696 A/m.

Thermal, Optical, and Microstructural Properties of Magnetron Sputter-Deposited CuSi Films forApplication in Write-Once Blu-Ray Discs

In this study, 16-nm-thick CuSi films were deposited at room temperature by DC magnetron sputtering. The thermal, optical, and microstructural properties of CuSi films were investigated in detail. Moreover, the CuSi film was further used as a recording layer for write-once blu-ray disc (BD-R) applications. Based on the result of the reflectivity–temperature measurement, the CuSi layer had a decrease in the reflectivity between 180 and 290 °C. The as-deposited CuSi film possessed the Cu3Si phase. After annealing at 300 °C, the Si atoms existed in the CuSi film segregated and crystallized to the cubic Si phase. The activation energy of Si crystallization in the CuSi film was determined to be 1.2 eV. The dynamic tests presented that the BD-R containing the CuSi recording layer had minimum jitter values of 7.0% at 6 mW and 7.2% at 9 mW, respectively, for 1× and 4× recording speeds. This reveals that the CuSi film has great potential in BD-R applications.

The Influences of Ru Seed Layer Microstructure on Structural Properties of CoCrPt-SiO2 Perpendicular Media

CoCrPt-SiO2granular film is well known as a perpendicular magnetic recording (PMR) media. To control the segregated structure of the recording layer, the role of the Ru underlayer is important. CoCrPt-SiO2perpendicular recording films were prepared by magnetron sputtering, with a series of Ru films as seed layer. The microstructure of Ru seed layers and their influences on the grain size, roughness and surface morphology of CoCrPt-SiO2granular films were investigated. It was found that the microstructure of seed layer obviously effected the structure and grain isolation of recording layers. The grain size and roughness of CoCrPt-SiO2recording layer were both increased with increasing the thickness of Ru seed layer. It is concluded that the thin and rough Ru seed layer is suitable for high-density magnetic recording media, and Ru seed layer with suitable thickness is very helpful for the achievement of perfect isolation and excellent magnetic properties. The result revealed that it was relatively easy for the CoCrPt grains to get perfect isolation with Ru thickness of 70 nm.

A study of perpendicular magnetic recording media using polarized SANS

The study of thin film magnetic systems that are structured on the nanoscale is an area of intense interest. Small-angle neutron scattering is an extremely powerful probe of nanomagnetism in the bulk, but in thin-film systems the experiments are challenging due both to the small scattering volume available and also to scattering from other sources such as the substrate and sample environment. We have demonstrated that such experiments are however possible in magnetic films as thin as 10 nm. A good example to illustrate this is the case of perpendicular magnetic recording media. These materials are found in all modern magnetic hard drives, the data storage technology that continues to be of tremendous commercial and technological importance. These media are advanced functional multilayered materials, containing an active recording layer of only around 10 nm in thickness. This recording layer is compositionally segregated into 8 nm-sized grains of a magnetic CoCrPt alloy separated by a thin oxide shell, typically SiO2. These media have their magnetic moments oriented perpendicular to the plane of the film. Determining the local magnetic structure and reversal behavior is key to understanding the performance of perpendicular media in recording devices. Polarised SANS has proved to be a very effective tool to measure these materials at a sub-10nm length scales. The signal of interest must however also be distinguished from the scattering from other layers in the structure, some of which are also magnetic. We will present a summary of some recent results on recording media, including measurements of the grain-sized dependent switching with and without the presence of an exchange spring. We will also briefly mention experiments that demonstrate the viability of extending this approach to measurement for lithographically defined structures similar to those for application in bit-patterned media, including 2d artificial spin-ice and structurally glassy arrays.