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Dr Dan A Allwood
EPSRC Advanced Research Fellow
BSc PhD MInstP CPhys
Address:
Department of Engineering Materials
Sir Robert Hadfield Building
Mappin Street, Sheffield, S1 3JD
Telephone: +44 (0) 114 222 5938
Fax: +44 (0) 114 222 5943
Email: d.allwood@shef.ac.uk
Dan Allwood was awarded an EPSRC Advanced Research Fellowship in 2004 entitled `Domain wall dynamics and interactions in magnetic nanowire networks´ and in 2005 joined the Sheffield Centre for Advanced Magnetic Materials and Devices in the Department of Engineering Materials. Previously, Dr Allwood worked in the University of Durham developing domain wall logic in magnetic nanowires. BSc and PhD awarded from the University of Hull, 1998.
Previously worked as a post-doctoral research assistant in:
University of Oxford, Department of Physics, 1997-1999.
Imperial College London, Department of Chemistry, 1999-2001.
Durham University, Department of Physics, 2001-2005.
Research interests
Dan Allwood´s research involves the understanding, analysis and application of magnetisation processes in magnetic thin films and nanostructures. A particular area of expertise is in domain wall processes in patterned magnetic nanowires. The extended geometry of these wires creates a simplified magnetic environment in which domain walls can be positioned. These nanowire systems have applications in information storage, information processing, sensors and biomagnetism.
Dr Allwood´s work has included the development of 2-D magnetic nanowire networks for controlling magnetic domain wall propagation. As part of this, he introduced magnetic domain wall logic in nanowire circuits, performed the first measurements of domain wall velocity in single layer nanowires and demonstrated domain wall propagation due to spin-polarised currents. Dr Allwood has developed a high sensitivity magneto-optical Kerr effect (MOKE) instrument for analysing individual nanostructures. He has also worked on optical methods to improve the MOKE response to isolated magnetic elements.
The magnetic films Dr Allwood works on are deposited on atomically-flat substrates using thermal evaporation or sputter deposition. Nanostructures are patterned either by electron-beam lithography or focussed ion beam milling. Topographic imaging of the structures usually requires either atomic force or scanning electron microscopies. The majority of Dr Allwood´s experimental research has used the MOKE technique to analyse the magnetic response of nanostructures and films. Recently, this has been complemented with studies using magnetically-resolving soft X-ray microscopy (with Dr Peter Fischer of the Advanced Light Source) and micromagnetic finite element modelling (with Professor Thomas Schrefl, University of Sheffield).
A range of projects have emerged recently in which Dr Allwood is using the stray magnetic field from patterned magnetic structures to control another system. This includes using domain walls in nanowires to trap and transport laser-cooled atoms (in collaboration with Durham University). Our calculations show that the atoms will be trapped exceptionally strongly and have very long spin coherence lifetimes. This offers a potential route to scalable quantum information processing. The stray field from simple magnetic elements is also being used to pattern biological Schwann cells to investigate growth of tissue for nerve repair.
Key projects
- Domain wall dynamics in planar magnetic nanowires. Investigating the influence of a domain wall’s environment on its dynamic behaviour in nanowires and the influence of stray magnetic fields between nanostructures on domain wall propagation. EPSRC funded.
- Magnetic soft X-ray microscopy of magnetic nanostructures. Investigating the use of magnetic X-ray transmission microscopy to image magnetisation changes in patterned elements. EPSRC funded.
- Developing trapping of laser-cooled atoms using stray magnetic field from magnetic nanowires, with Professor Mike Gibbs (Sheffield), Professor Thomas Schrefl (Sheffield), Dr Ifan Hughes (Durham) and Professor Charles Adams (Durham). EPSRC funded.
- Magnetic trapping of Schwann cells for growth of nerve tissue, with Dr John Haycock (Sheffield) and Professor Thomas Schrefl (Sheffield). BBSRC funded.
- Development of magnetoresistive sensors for magnetic nanowire applications, with Professor Thomas Schrefl (Sheffield), Dr Chris Marrows (Leeds) and Dr Gavin Burnell (Leeds). EPRSC funded.
Professional activities and recognition
- Member of the EPSRC Materials Peer Review College.
Key publications
- D.A. Allwood, G. Xiong, M.D. Cooke, C.C. Faulkner, D. Atkinson, N. Vernier and R.P. Cowburn, 'Sub-micrometer Ferromagnetic NOT-gate and Shift Register', Science 296 (2002) 2003.
- D. Atkinson, D.A. Allwood, G. Xiong, M.D. Cooke, C.C. Faulkner and R.P. Cowburn, 'Magnetic Domain-wall Dynamics in a Submicrometre Ferromagnetic Structure', Nature Materials 2 (2003) 85.
- N. Vernier, D.A. Allwood, D. Atkinson, M.D. Cooke and R.P. Cowburn, 'Domain wall propagation in magnetic nanowires by spin-polarized current injection', Europhys. Lett. 65 (2004) 526.
- D.A. Allwood G. Xiong, C.C. Faulkner, D. Atkinson, D. Petit, and R.P. Cowburn, 'Magnetic domain-wall logic', Science 309 (2005) 1688.
- D. A. Allwood, T. Schrefl, G. Hrkac, I. G. Hughes and C. S. Adams, ‘Mobile atom traps using magnetic nanowires’, Appl. Phys. Lett. 89 (2006) 014102.
- M. T. Bryan, T. Schrefl and D. A. Allwood, ‘Symmetric and asymmetric domain wall diodes in magnetic nanowires’, Appl. Phys. Lett. 91 (2007) 142502.
- D. A. Allwood, P. R. Seem, S. Basu, P. W. Fry, U. J. Gibson and R. P. Cowburn, ‘Over 40% transverse Kerr effect from Ni80Fe20’, Appl. Phys. Lett. 92, (2008) 072503.
- M. T. Bryan, T. Schrefl, D. Atkinson, and D. A. Allwood, ‘Magnetic domain wall propagation in nanowires under transverse magnetic fields’, J. Appl. Phys. 103, (2008) 073906.
Research group
PDRAs:
Dr Matthew Bryan
Dr Jill Weaver
Dr Isaac Luxmoore
PhD Students:
Mr Matthew Bryan
Mr Swaraj Basu
Mr Simon Bance
Research centres
Sheffield Centre for Advanced Magnetic Materials and Devices
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