Physics considerations in the design of three-dimensional and multilevel magnetic recording

Abstract

The purpose of this paper is to explore three-dimensional magnetic recording as a next generation recording technology. To defer the superparamagnetic limit in magnetic recording substantially beyond the 1Tbit∕in.2 mark, it is proposed to stack magnetic bits in a third (vertical) dimension. The vertical stacking underlies the concept of three-dimensional (3D) magnetic memory and recording—the primary subject of this paper. A clear distinction between absolute 3D memory and its trivial multilevel implementation is drawn. The paper focuses on the study of the media design and write and read processes. To minimize the intersymbol interference and improve stability, it is proposed to pattern the recording media in all three dimensions. Basic Co∕Pd-based 3D recording media necessary for this study are fabricated using cosputter deposition. Focused-ion-beam-based fabrication is used to pattern the recording media into nanoscale bit cells. The physics of 3D magnetic recording is also investigated theoretically with Landau-Lifshits-Gilbert-based micromagnetic modeling. The ultimate goal of this paper is to help understand the physics of 3D and multilevel magnetic recordings and trigger wide interest in the studied concept.

Study of Co/Pd multilayers as a candidate material for next generation magnetic media

“…11 By stacking recording layers in a third dimension we could effectively increase the areal density of magnetic storage beyond 10 Tbits/ in. 11 By stacking recording layers in a third dimension we could effectively increase the areal density of magnetic storage beyond 10 Tbits/ in.…”

Sixteen-state magnetic memory based on the extraordinary Hall effect

“…Achieving Tb/in 2 recording densities will require a challenging fabrication of sub-10 nm discrete magnetic islands covering a full disk with tight spacing and narrow switching field distribution. Another approach to increasing storage density without reducing the bit size is by increasing the number of bits stored within each dot in a multilevel storage [2].…”

Three-dimensional magnetic recording using ferromagnetic resonance

“…Actually, there have been several research studies on the application of this method to multilayer recording. [20][21][22][23] According to them, when each recording layer is provided with a different switching field (H sw ), every magnetization state in the multilayer medium can be achieved by reversing the recording layers sequentially from the one with the highest H sw to that with the lowest H sw . This method, however, requires a head element to stay on one place of the medium for a certain period of time to conduct sequential switching, which slows device operation.…”