NGCM-02: Computer simulations of magnetic skyrmions
New effects have been predicted based on the so-called Dzyaloshinskii-Moriya Interaction (abbreviated as DM interaction or DMI) in magnetic nanostructures. For the right materials, this interaction can create magnetisation vector field configurations that look like a hexagonal array of vortex-like objects. These objects are called Skyrmions after Tony Skyrme who proposed their existence in 1962 (in a different field).
By now, such Skyrmions lattices have been observed experimentally, and triggered significant research activity. Each Skyrmion looks like a vortex with typical diametre between 3nm to 100 nm, depending on material parameters. The skyrmions form a hexagonal lattice in the thin-film with the skyrmion-skyrmion spacing of similar size as the skyrmion diametre. While the atom spacing in the atomic lattice is about 0.3nm, the Skyrmions form a meta-lattice where the lattice constant is about 1 to 2 orders of magnitude larger.
Inspired by this recent experimental discovery, further works have shown remarkable properties of skyrmions: due to the unexpected stability of the skyrmion lattice, they could potentially be used to record data at the nanoscale . It has also been found that a very low electric currents can drive the skyrmions through the film, which opens the door for a low-energy realisation of the currently much researched race-track memory device. This device has the potential to replace harddisks with a new technology that combines high capacity with low power requirements, and can sustain an unlimited number of read-write cycles.
In this project , we will extend the established micromagnetic framework (as implemented in the Nmag and OOMMF simulation software, for example) with the interaction terms that allow to observe and study the skyrmion phase; leading to the emergence of skyrmion formation. There is a multitude of interesting studies awaiting, including the dynamics and thermodynamics of skyrmions, and their interaction with spatially confined structures (leading the path towards logic networks and storage devices). How does a skyrmion lattice melt if the temperature is increased - do skyrmions start to move around each other like a skyrmion liquid? In a long thin strip of a magnetic film, can we see one row of skyrmions form? If so, below which strip width do these skyrmions not fit into the strip anymore? How stable are these skyrmions with respect to thermal fluctuations? We work alongside experimentalists to help guide and interpret their work to study skyrmions in magnetic systems experimentally, in this new area of research in advanced magnetic nano materials.
 http://www.southampton.ac.uk/~fangohr/vacancies/skyrmions.html for further details.
This project is run through participation in the EPSRC Centre for Doctoral Training in Next Generation Computational Modelling (http://ngcm.soton.ac.uk). For details of our 4 Year PhD programme, please see http://www.findaphd.com/search/PhDDetails.aspx?CAID=331&LID=2652
For a details of available projects click here http://www.ngcm.soton.ac.uk/projects/index.html
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