PhD project opportunity: HAMR - Modelling and Simulation of Heat Assisted Magnetic Recording

Eligibility: Please see http://www.ngcm.soton.ac.uk/studentships.html

Image: (left) shape of magnetic grains (diametre ~10nm) used in data storage. (right) temperature diffusion in future technology. See text and images at end of page for details.

Introduction

Magnetism and technology exploiting magnetic effects are of great importance: at the macro scale, magnets are used in energy generation, motors, and medical equipment. At the microscale, the combined advancement of magnetic data storage technology and silicon chips development has paved the way for the information age. High capacity magnetic data storage is essential in many commercial products, and underpins business models such as Google, YouTube, eBay and Amazon. Similarly, data-based initiatives such as Wikipedia (with substantial and mostly positive effects on societies' education) are only possible due to high capacity data storage.

Project outline

This PhD research project researches the next generation magnetic storage media using computer simulation together with international partners in academia and industry.

Currently, magnetic data is stored by changing the magnetisation of about about 100 grains in the magnetic data storage medium on the platters of a hard disk drive using a magnetic field that emerges from the write-head. To maintain the exponential increase of storage capacity over time, this concept needs to be changed fundamentally, and in this research project we explore possible designs for this new technology by bringing together our skills in micromagnetic simulation and design optimisation.

HAMR

In more detail, it is now becoming apparent that the magnetic recording industry is moving towards Heat Assisted Magnetic Recording (HAMR, pronounced as 'hammer') to be realised in products within approximately 5 years. In this proposed technology a small laser spot heats the magnetic medium and a (relatively weak) magnetic field will reverse the grains in the area of the heated spot. This allows to make the grains smaller and thus increase the storage capacity. However, the physics and engineering of magnetisation statics and dynamics at the nanoscale in the presence of spatially and temporally rapidly changing temperatures is mostly unexplored, and shows a multitude of complex emerging phenomena. The magnetisation at the nanoscale (to so called micromagnetic model) is described through non-linear partial differential equations.

The group has a track record in micromagnetic simulation and provided a number of open source tools to the community, most notable the finite element micromagnetic simulation suite Nmag that is used worldwide by more than 100 groups. In this project, you will be working on and with the successor of the Nmag package. Placements/visits of project partners (Germany, US, Singapore, UK) is possible and desirable.

Skills

Experience with any of the following will be advantageous but not required as training will be be provided as necessary:

• Computational physics or Engineering
• Programming experience (in particular Python and C or C++)
• Use of Linux
• 3d Visualisation tools
• Ordinary and partial differential equations
• Micromagnetic modelling

If you wish to discuss any details of the project informally, please contact Hans Fangohr, CED research group, Email: h.fangohr@soton.ac.uk, Tel: +44 (0) 2380 59 8345

Please contact Hans Fangohr <fangohr@soton.ac.uk> for informal queries, expressions of interest or applications.

Image: A model of the random granular grains that are magnetised collectively to represent a bit. The colour has no physical meaning here (it shows the order in which the mesh generator has placed the nodes in the finite element mesh).

Image: Schematic represenation of thermally assisted writing process on patterned media. Spot 1 is heated for 1 nano second (to 800K), then spot 2 is heated (instantaneously) to 800K. The colourmap shows the diffusion of temperature in the material. The last plot shows isosurfaces, i.e. layers of constant temperature in the material. The spacing of the iso surfaces is 50K. Here, the so-called 'bit patterned media' is modelled where there is only one magnetic element (the cylindrical objects) per bit. The relevant question is: when the writing moves to spot 2, will spot 1 we cooled sufficiently, not to be accidentially reversed through the write field that was meant for spot 1.

This project can be funded through the Doctoral Training Centre is Complex Systems Simulations (see http://www.icss.soton.ac.uk).