Nano-sized ferromagnetic platelets could be used for stable magnetic data storage or magnetic vortex cores. These are magnetic structures shaped like needles and have a diameter of 20nm.
A team at the Max Planck Institute for Intelligent Systems in Stuttgart is researching the ferromagnetic platelets that are fabricated from Permalloy, an alloy of nickel and iron. Their shape helps create a magnetic structure that looks like a shooting target. The circular vortice pattern alters in the middle of the platelet.
Hermann Stoll who led the team said that it is not possible to form concentric circles with matches since they are too long. Pushing them out of the plane makes them resemble a needle perpendicular to the plane. In the vortex platelet, a magnetic field needle is created, pushing out of the vortex core, measuring 20nm in diameter. It is able to store tiny pieces of information since they are pointed in both upward and downward directions.
This direction can be changed with an external strong magnetic field. This feature helps it to resist other interfering magnetic fields. But the stored information cannot be played back and processed.
The Max Planck Institute has partnered with the Helmholtz Zentrum at BESSY II in Berlin to design a scanning X-ray microscope and have developed a system, which could switch a vortex core within 200 picoseconds. The process produces spin waves that can change the vortex core. The team says that this mechanism generated spin waves and it was possible to reduce the change-over time by an additional further factor of 10. When the switching is done using spin waves, the core did not shift. But when the switching was handled more slowly with megahertz frequencies, the core needed to be shifted away from its equilibrium, revealing that a storage bit needed more space. This technique allows the platform to be reduced in size if storage date that act according to this mechanism are developed for future application.
Source: http://www.mpg.de