Nano Data Storage: Nanofabrication of magnetic structures for data storage applications

Introduction
One major commercial application for the fabrication of nanoscale magnetic structures is in magnetic data storage. The now ubiquitous hard disk drive (HDD) has been one of the greatest technological achievements of the past half-century, with the growth of the storage capacity of HDDs being achieved by scientific advancements, such as the introduction of GMR heads, which won the 2007 Nobel Prize for Physics. However, it is widely accepted that current approaches will fail to deliver the storage capacities required by tomorrow’s technologies. The use of bit-patterned media (BPM) is seen as one solution to this problem, whereby a single data bit is stored to a single magnetically isolated element. The challenge in developing BPM lies in the fabrication of island arrays at dimensions close to the limits of today’s lithographic approaches (1Tbit/in2 requires islands to be spaced on a 25nm x 25nm lattice with islands <20nm in diameter). Island arrays have been successfully produced at densities approaching 1Tbit/in2 by etching continuous films into islands or by depositing films onto pre-patterned substrates, however, the resulting nanostructures have a large variation in structural and magnetic properties that makes them unattractive for use in BPM. To enable the commercial realisation of BPM these variations must be controlled.

Project
The challenging aim of this project is to produce patterned magnetic nanostructures with controlled properties for us in future BPM systems, through the development of novel media and fabrication processes. The project will involve the use of thin film fabrication and materials processing techniques that will push the limits of the nanolithography facilities available in the Manchester Centre for Mesoscience and Nanotechnology. The skills developed are essential for the development of any nanotechnologist and are applicable to nanofabrication in areas outside of data storage.

The NEST Group
The Nano Engineering & Storage Technology (NEST) group is housed in an integrated suite of staff offices, general-purpose laboratory space and class 100/1000 cleanrooms. The group is a founder member of the Manchester Centre for Mesoscience and Nanotechnology (CMN), which is based in the group’s laboratories and contains state of the art lithography tools for the fabrication and visualisation of nanoscale structures. The group also has facilities for characterising magnetic media including a purpose built alternating gradient field magnetometer and an ADE Technologies vector vibrating sample magnetometer.