Module 3: Nanoscale magnetic materials and devices (MAT6390)
A review of basic magnetic properties, how nano scale magnetic devices can be made, and the exciting scientific and technical opportunities these are opening up.
Above: Photograph of equipment used for preparing nanostructures.
Magnetism and magnetic materials are endemic to much of today's science and technology.
The drive for miniaturisation of materials and devices has presented a number of scientific challenges.
This module will review basic magnetic properties, and demonstrate how control of the nanostructure in bulk materials, optimised growth of thin films and multilayers and patterning to nanoscale are opening up new areas of science and technology.
Outline syllabus
- Overview/revision of magnetism in solids.
- Property/nanostructure relationships.
- Fabrication and properties of nanostructured magnets.
- Probes of nanomagnetic properties.
- Electronic magneto-transport.
- Micromagnetic modelling.
- Applications and devices.
Above: Conduction electron paths with both layers magnetised in the same sense and below in opposite senses.
Magnetotransport
With both magnetic layers magnetised in the same sense, conduction electrons with spin parallel to the material's magnetisation move freely; electrons of opposite spin are scattered strongly — a low resistance state (see diagrams left).
With the layer magnetisations anti-parallel, both spin channels are scattered in the layers — a high resistance state.
Spin electronics has much to offer for next generation devices.
Modelling & applications
The ability to model the field response of magnetic elements is becoming of increasing importance. Micromagnetic simulation, Preisach and other models will be discussed. Students will gain experience of simulation software.
Micro-electromechanical (MEMS) applications will be discussed, together with other devices for field sensing.
Above: The domain structure of a magnet.
Basic physics & characterisation methods
Covering bulk magnetisation, domain structure and magnetostriction. Plus looking at nanostructure growth (photo above left), magnetic force microscopy and magneto-optics probes.
Nanocomposite magnets
Nanocomposite magnets, where the grain size is reduced to the nanometre scale, offer both the softest (FeSiBNbCu) and the hardest (NdFeB) magnetic materials currently available. Understanding the physics of exchange interactions and anisotropy control is vital to the success of these materials. Their continued development has had a major impact on the efficiency and size of electric motors and machines.
Back to: Nanomaterials for nanoengineering
