EPSRC DTP PhD studentship: Magnetization dynamics of novel magnetic recording media induced by femtosecond optical pulses

University of Exeter - College of Engineering, Mathematics and Physical Sciences

Main supervisor:   Prof R. J. Hicken (University of Exeter)
Co-supervisor:  Dr G. Hrkac (University of Exeter)

In magnetic hard disk drive technology, data is stored within a multilayer thin film on the surface of the disk. 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, essentially a partial domain wall, 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 has 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. The project will provide 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.

[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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South West England