65 Gbits/in.2 quantum magnetic disk (abstract)

Abstract

Quantum magnetic disk (QMD), proposed recently, offers a new paradigm for ultrahigh density magnetic recording. In a QMD, each bit is represented by a prepatterned nanoscale single-domain magnetic pillar or bar that was uniformly embedded in a nonmagnetic material on a disk. The size and shape of each bit is well controlled during the fabrication to ensure single magnetic domain formation, therefore the magnetic moment of each bit has only two quantized states: equal in magnitude but opposite in direction. Compared to conventional magnetic disks, the QMD offers many unique advantages in writing, reading, and tracking. In this article, we report the fabrication of both longitudinal and perpendicular magnetization QMDs and their investigation with scanning electron microscopy, atomic force microscopy, and magnetic force microscopy. Both QMDs were fabricated using electron beam nanolithography, reactive ion etching, and chemical mechanical polishing. We will also discuss QMD fabrication techniques which do not involve conventional lithography. The perpendicular QMD structure consists of 50-nm-diam nickel pillars uniformly embedded in 200 nm thick SiO2 with a surface roughness of 0.5 nm rms. The pillar array has a period of 100 nm which corresponds to a magnetic storage density of 65 Gbits/in2—over two orders of magnitude greater than the current state-of-the-art magnetic storage density.