GOALI: Si-doped Co/Pd Multilayers on ITO Seedlayers for Perpendicular Magnetic Recording Media

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This proposal describes research and outreach involving a complementary team of experimentalist, theorist, and industry liaison. The goal is to find a magnetic medium that can reach the full potential of perpendicular recording and generate opportunity for even higher density approaches such as heat-assisted magnetic recording. For this purpose, this work proposes research on Co/Pd based multilayer media, owing to their high interface-induced perpendicular anisotropy, high coercivity and high squareness. Currently, industry focuses on alloy based materials due to their lower noise; however, the multilayers appear to offer the best chance of reaching extremely high density magnetic recording with good thermal stability. Dissemination of the research experience and the results of the research is another important aspect of this work. Both undergraduates and graduate students will be involved in this media research, and, through an REU program currently in place, local science teachers will have the opportunity to be involved during their summer break. In line with IBM expectations, time and budget allocations have been made to visit IBM both to allow the PIs to better understand IBM testing results and to give IBM updates on the current progress and directions. Disks of our media will be made available to other companies as well: historically many companies have requested materials from the PIs and, in at least three cases, returned detailed results of their tests. Frequent visits to other industrial organizations by the PIs will be continued, where they will report the results of this research. All of this should greatly aid technology transfer. Research The microstructure of Co/Pd multilayers, namely grain size and magnetic separation between the grains, is extremely important in reducing noise and achieving high recording densities. The proposed work will use seedlayers and doping to control the microstructure, and therefore the magnetic properties of the multilayers. In this study, 0-2nm of InSn alloys, with altering degrees of oxygen content will be grown under varied experimental conditions to determine the optimal crystal structure for seeding Co/Pd media. Preliminary studies suggest that this will increase coercivity, relative to alternate seed layers, without the grain-enlarging necessity of high temperature deposition. The purpose of a dopant in these multilayers is two-fold. First, a dopant that migrates to the grain boundary inhibits grain growth and, second, it helps ensure a nonmagnetic grain boundary. In the proposed work, Si will be closely examined owing to its theoretical segregation from Co and Pd. The theoretical investigations will include interpretation of experimental data and suggestion of new material approaches. Theory will play a particularly prominent role in selecting the best disks for the industrial partner (IBM) to finish and test on a spin stand, and in interpreting the ensuing data. New material approaches or, as is more likely, modification of the proposed ones to further improve performance will also stem directly from this theoretical work. Particular effort will be made to isolate the effects of Si from the interface and to consider alternate dopants such as Ge.