Magnetisation dynamics in energy assisted magnetic data storage materials

Magnetisation dynamics is a very broad research field and our interest is in the dynamics of thin film materials and particularly nanomagnetic systems. This project is focussed on developing /experimental understanding/ of the physical properties which control the dynamic response of materials. The dynamic behavior of magnetic materials is critical in any data storage application as these systems are increasingly required to supply and record information at GHz rates. Very recently a new class of energy assisted recording technology where microwave power is provided in additional to a short magnetic field pulse has been proposed. Is this the principal behind microwave assisted magnetic recording (MAMR). Here the excitation of magnetization dynamics where a precession of the moment is established allows the magnetization to switch at lower applied fields than would otherwise be the case allowing higher anisotropy materials to be used and so postponing the point at which superparamagnetism degrades data retention.

In this project involves using ferromagnetic resonance (FMR) to characterize the damping parameter a in data storage materials. The work will involve creating devices and techniques for FMR experiments on novel perpendicular exchange spring materials. Some earlier work can be found in ref. [1] where a continuous wave system was used to study longitudinal data storage media. These measurements not only allow the anisotropy field to be probed but also provided new information on the damping processes in these materials.


[1] "High field ferromagnetic resonance measurements of the anisotropy field of longitudinal recording thin-film media"
C.J.Oates, F.Y.Orgrin, S.L.Lee, P.C.Riedi, G.M.Smith, T.Thomson J. Appl. Phys. 91(3) (2002) 1417-1422