EPSRC CDT in Metamaterials: Magnetization dynamics of magnetic metamaterials induced by femtosecond optical pulses

University of Exeter - Departments of Physics and Astronomy, and Department of Engineering

The studentship is part of the EPSRC Centre of Doctoral Training in Metamaterials (XM2), www.exeter.ac.uk/metamaterials. Our aim is to undertake world-leading research, while training scientists and engineers with the relevant research skills and knowledge, and professional attributes for industry and academia.

Joint supervisors:  Prof R. J. Hicken, Dr G. Hrkac

The multilayer thin film coating on a magnetic hard disk is an outstanding example of a magnetic metamaterial.  By tailoring the interfaces and the lateral grain structure, the properties of a larger storage “bit” are optimised.  The need to reduce the bit size while retaining thermal stability has led to the development of heat-assisted magnetic recording.  This project will explore the response of magnetic media to stimulation by femtosecond laser pulses.  We will explore exchange spring systems in which alternating layers of hard and soft magnetic material are exchange coupled at their interfaces.  Application of a magnetic field produces winding of an exchange spring within the soft layer, which causes the hard layer magnetization to reorient when its magnetic anisotropy is quenched by the laser pulse [1].  While modelling allowed us to explore the conditions for full magnetic switching, only reversible dynamics short of switching were observed experimentally. The proposed project will explore a wider range of epitaxial exchange springs, supplied by Prof Thorsten Hesjedal at Oxford University, and attempt to observe full switching. Samples for opto-magnetic switching, induced by circularly polarized light, will be supplied by Professor Robert Bowman at the ANSIN centre, Queens University Belfast, and by Seagate Technology.  As a member of the CDT you will receive a broad training, which will promote the transfer of ideas to other areas of nanotechnology, and develop transferable skills suited to a wide range of future careers, for example in the magnetic recording industry.

4-year studentship: for UK/EU students, the studentship includes tuition fees and an annual stipend equivalent to current Research Council rates; for international students (non-EU) a very small number of fees only studentships may be available

[1] “Ultrafast optical parametric pumping of magnetization reorientation and precessional dynamics in DyFe2/YFe2 exchange springs”, L. R. Shelford, Y. Liu, U. Al-Jarah, P. A. J. de Groot, R. C. C. Ward, and R. J. Hicken, Phys. Rev. Lett. 113, 067601 (2014).

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