2009
Magnetisation in hollow ferromagnetic pyramid. (More detailed description to follow soon, 17 October 2009). The color represents demagnetisation energy density. 2008
Schematic represenation of thermally assisted writing process on patterned media. Spot 1 is heated for 1 nano second (to 800K), then spot 2 is heated (instantaneously) to 800K. The colourmap shows the diffusion of temperature in the material. The last plot shows isosurfaces, i.e. layers of constant temperature in the material. The spacing of the iso surfaces is 50K.  The electric potential (shown through black isosurfaces) and the associated current density that results from the electric field which is visualised through coloured cones. The size of the cones corresponds to the magnitude of the current density. The interaction of electric currents with magnetisation (not shown) is an area of big technological interests. Weak currents are used to probe the magnetisation, and large currents to manipulate the magnetisation. 2007 Left: Scanning Electron Microscope picture of sphere-like Nickel droplets (diameter of each is 500nm). Right: computer model. Computer simulations and experiments have been carried out to study the potential of such nano structures as bit patterned media in the next generation of magnetic data storage devices.  Top: magnetisation vectors in a ferromagnetic nano structure of size 50nm by 10nm by 10nm. This tiny device can be used to generate electromagnetic waves at frequencies (bottom plot) in the 10 GHz range by running a spin-polarised electric current through it. Applications include microwave assisted recording and wireless communications.  Computer simulation results of ferromagnetic nickel half sphere of diameter 350 nm. Left: a vortex has formed with core pointing in the +x direction (at an applied field of 80mT). Right: a vortex has formed around a core pointing roughly in +z direction (at an applied field of 65mT).  Computer simulation results of vibration modes of Carbon Nano Tubes. The image shows a particular deformation type called bending mode of a short carbon nano tube with 240 carbon atoms.  The image shows details of the vortex ring formed by a rising bubble in the atmosphere of a cluster of galaxies. Color represents density distribution with values between 1000 particles per cubic metre (green), and 1 particle per cubic metre (red). The arrows show direction of the velocity vectors with large arrow representing about 10,000 metres per second. Such rising entropy bubbles are thought to be crucial in the cooling process of galaxy clusters.  The magnetisation in a Nickel disk (diameter 100 nano metre, height 20 nanometre) forms a vortex. The magnetisation vectors in the vortex core point upwards to minimise the overall energy. Such magnetic nano structures could be used as the next generation of magnetic media. |
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