GOALI: High Magnetic Anisotropy Materials for Ultrahigh Density Heat-assisted Magnetic Recording Media.

Georgetown University, Washington DC

Investigators

Abstract

Over the last six decades, the areal density of magnetic recording has increased by eight orders of magnitude. These rapid advancements have fundamentally changed information technology and the way of life. The information is stored in tiny magnets, like compasses with nanometer sizes. As each bit of information is stored over an ever-smaller volume, it is essential to use materials that are still stable at extremely small dimensions against thermal effects. This material property is known as the magnetic anisotropy, which anchors magnetic moments in place, enabling their practical use. This project aims at realizing materials with high magnetic anisotropy using convenient and benign synthesis conditions, combined with control over the material properties, towards applications in next generation ultrahigh density magnetic recording media and rare-earth-free and precious-metal-free permanent magnets. This GOALI partnership between U.C. Davis and Seagate offers an exciting opportunity to rapidly transfer research results into technology. This would potentially speed up the adaptation of the emerging heat-assisted magnetic recording technology. Advances in more powerful permanent magnets would impact numerous industry sectors, including hybrid and electric vehicles, magnetically levitated trains, wind turbines, power storage, magnetic refrigeration, etc. The partnership also provides opportunities to train junior researchers in industry research and development laboratories, in addition to excellent exposure to research experience in university and national laboratory and user facilities. The team plans to initiate and actively participate in a variety of efforts to broaden participation from underrepresented groups through internships, graduate course offering, exchange visits with Seagate, and other specific programs at the Magnetism Conference. High magnetic anisotropy materials have critical applications in next generation ultrahigh density heat-assisted magnetic recording media as well as high energy density permanent magnets. Alloys of ordered FePt in the L10 phase is an ideal candidate for recording media applications. However, a critical challenge has been the high annealing temperature necessary to transform the as-deposited low anisotropy phase into the desirable high anisotropy one. This project will achieve high magnetic anisotropy L10 FePt-based thin films using atomic-scale multilayer sputtering and rapid thermal annealing. Magnetic properties of these materials will be tailored to achieve the desirable high anisotropy, large saturation magnetization, and low Curie temperature using ternary FePt-based alloys through proper tuning of the effective valence electron number. These approaches will be extended to realize L10 FeNi films that are alternative type of permanent magnets using earth abundant elements. A true understanding of the disorder-order phase transformation in these thin films will be gained, and quantitative evaluation of the phase fractions will be obtained. The partnership between U.C. Davis and Seagate will help to achieve L10 FePt and FeNi based alloys that can be readily synthesized, with controlled anisotropy at the atomic scale and minimized switching field distribution. Such materials have potentially transformative technological impacts, in speeding up the adaption for the emerging ultrahigh density heat-assisted magnetic recording technology and in the realization of high energy density permanent magnets that are rare-earth-free and precious-metal-free.