Physics of rare - earth transition metal permanent magnets: new magnetic sensors

There is a strong and growing demand for permanent magnets for use in diverse areas, including sensors and motors, with a requirement to develop new magnetic materials which will maintain their performance at higher temperatures (> 400 K). At the Universities of Warwick and Birmingham we are starting an integrated experiment-theory program to understand the magnetic properties of new rare-earth - transition-metal permanent magnets and develop these materials for applications. On the experimental side of this EPSRC funded project, "Investigations of the Physics underlying the principles of design of Rare Earth Transition metal permanent MAGnets" (PRETAMAG), we are looking for a postgraduate student to help with the characterisation of magnetic materials and to investigate the potential for their incorporation in to sensors.

Most of the current commercially available permanent magnets contain rare-earths, and the growing demand and instability of rare-earth supplies presents a challenge. The development of magnets containing less rare-earth material with higher Curie temperatures (Tc), and their characterisation, is key to producing viable alternatives and pushing their capabilities to higher temperature operation. PRETAMAG is developing experiments and the theoretical basis for understanding the behaviour of new rare-earth - transition-metal permanent magnets. Polycrystalline and single crystal samples of materials such as SmCo5, GdFe2, and GdCo5 will be produced and characterised using a range of experimental techniques, including magnetometry, transport, and ultrasound measurements over a range of temperatures and magnetic fields. The results obtained will be used to understand the behaviour of the materials and identify suitable alternatives to those currently used. The materials showing the most promise will be formed into bonded permanent magnets and used to build test sensor devices such as electromagnetic acoustic transducers (EMATs), a non-contact ultrasonic transducer. EMATs typically contain a NdFeB permanent magnet, with the maximum inspection temperature limited by Tc and the availability of water cooling. Measurements using these sensors at elevated temperatures will give an understanding of the anisotropy of the magnetic materials, their behaviour at higher temperatures, and show the potential for sensors based on the materials.

The project will involve material characterisation. It will also involve sensor development and offers the opportunity to work alongside theorists and other experimentalists to deliver impact and engage with industry. For further information about the project, please contact Dr Rachel Edwards ([Email Address Removed]) or Dr Martin Lees ([Email Address Removed]).