Novel Synthetic Magnetic Structures for All-Optical Magnetic Recording

"""Magnetic data storage is central to societal exploitation of information technology. Bulk data storage is by hard disk drives in the 'Cloud'. Currently, these drives use magnetic writing (electromagnetic) and reading (spintronics). Heat Assisted Magnetic Recording (HAMR) drives are just entering the market and they replace the purely electromagnetic writing with heat applied via a near-field plasmonic interaction on the disk surface. Beyond HAMR, a decade from now, there is the potential to do away with the energy consuming electromagnetic writing process and use an all-optical means to switch and encode magnetic data on the disk. This requires convergence of three new research challenges 1. New materials that exhibit helicity independent, deterministic, magnetic switching, 2. Superior near field irradiation schemes and 3. The use/development of microscale picosecond (ps) laser sources. This project will address aspects 1 and 3.

We are currently engaged in a collaboration to explore the materials and the physical mechanisms that could be used in all-optical switching (AOS). To date we have demonstrated the effects with thin synthetic ferrimagnets comprised of multilayers such as Ni3Pt (7nm) / Ir (0.5nm) / Co (1nm) [2] and Ni/Pt superlattices . We now wish to converge towards conventional HAMR based magnetic media based on the FePt alloy. This will involve the synthesis of new synthetic magnetic multilayers and their magnetic characterisation (magnetometry, ferromagnetic resonance etc). The materials development work may also involve a session/s at the DIAMOND synchrotron facility, using XMCD to probe switching dynamics of constituent atoms/layers . Further there is scope to interact with a related project at UoG that will use HRTEM and Lorentz imaging to elucidate the magnetic domain structure in these novels system which in combination with this project will give us a fuller understanding of the development of these new materials. Secondly, to allow us to screen newly developed materials for the desirable AOS behaviour ahead of more intensive characterisation with collaborators at Exeter University we aim to create a small integrated photonic test bed system that uses new ps lasers to do basic far-field laser excitation of AOS materials to demonstrate use of microscale ps lasers in AOS.

There is the scope for undertaking computer based simulations using ab-initio code [http://vampire.york.ac.uk] and/or packages such as OOMMF [https://math.nist.gov/oommf/] or mumax3 [https://mumax.github.io] depending upon student interests. You will also get training & exposure to equipment for materials processing & characterisation including deposition systems & electron & focused ion beam microscopes.

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