My research group is currently involved in a number research projects in the areas of nanoscale spintronic devices and nanoscale biological applications. Eight post-doctoral researchers and five PhD students are engaged across the projects. My philosophy of research is to span a spectrum from applied physics through technology to commercialisation

Security, Sensors and Nanomagnetism

Laser Scattering for Security

When laser light scatters from a surface it carries information about the microscopic and nanoscale roughness which is inherently present in any real surface. This applied physics project investigates how that information can be used to form a unique and uncopyable identity code that can be used to detect and prevent counterfeiting and smuggling. Unlike most security techniques that involve adding some authentication feature, this method relies on naturally-occurring features. As a result it is extremely difficult to attack and yet very easy to use. The project is carried out in close cooperation with an Imperial spin-out company Ingenia Technology Ltd, which is seeking to bring this technique (known as Laser Surface Authentication) into widespread use throughout industry. Successes to date include the use of the LSA signature to prevent smuggling of high value perfume and to protect nuclear facilities.

Laser light scattering diffusely from naturally-occurring roughness on the surface of a valuable document.

The surface of a plastic credit card as seen under Atomic Force Microscopy. The large amount of nanoscale structure forms an excellent security feature.

Nanomagnetic 3D Magnetic Memory Devices

Magnetic materials are already widely used in data storage in the form of the hard disk drive. As electronics becomes increasingly portable, there is a strong desire to move away from mechanical disks to solid-state (chip based) data storage technologies. Although semiconductor memories such as Flash memory exist and are very successful, their cost-density (price per bit stored) is far from that of the hard disk drive. The ultimate data storage technology would combine the cost per bit of a mechanical hard disk drive but would have the portability and reliability of a solid state chip. Limits on lithography mean that it is very difficult to pack more data bits into the same area on a chip. If a quantum leap in memory performance is to be made it must come by building upwards from the plane of the chip to form 3-dimensional solid state memories. This project seeks to investigate the physics needed to enable such a future technology.

Two approaches are adopted. The first uses magnetic domain walls in magnetic nanowires. Magnetic nanowires can be thought of as conduits or conductors for domain walls, allowing a new paradigm of integrated circuit in which electrical currents flowing through transistors are replaced by magnetic domain walls flowing through nanowires.

The second approach uses novel solitons in 3-dimensional magnetic nanostructures. A newly funded £2.5 million project called 3SPIN begins in this research group in February 2010 and will last for 5 years. It aims to investigate the physics of these currently unobserved solitons and to attempt to build the world’s first data storage device based on solitons in magnetic nanostructures.

A 32-bit magnetic nanowire non-volatile data storage device built within this research group. Data are written by nanosecond current pulses at the left hand side of the device, launching domain walls into the nanowires. The domain walls then pass through a 32 bit shift register made from magnetic nanowires in the centre of the device before passing back out for read-out on the right hand side.

A proposed 3-dimensional data storage device based on domain walls in magnetic nanowires.