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Portraits of mankind on a postcard

Keeping up with the information flood demands durable and ever denser storage media. A technique being developed by researchers in Dresden uses modified films made of diamond-like carbon. The resulting storage capacity is fifty times more than the best disk drives.

The basic principle of data storage revolves around the permanent modification of specific material characteristics. In addition, it requires a suitable instrument to read and write the data. CDs and DVDs use tiny pits and laser technology to store information. Hard drives save data within minuscule magnetic domains that the read / write head creates, reads or deletes. Whatever the medium, there are physical limits to storage density. With optical storage, density is restricted by the laser wavelength. Hard drive capacity is limited by the size of the magnetic particles. Below a certain particle size, the movement of atoms causes its magnetic properties to be lost, and hence the data. Researchers at the Fraunhofer Institute for Material and Beam Technology IWS in Dresden develop a new approach based on diamond-like carbon films. For the instrument, ultra-fine metal tips like those found in scanning tunneling microscopes (STM) are used. Thomas Mühl, physicist at the Leibniz Institute for Solid State and Materials Research IFW in Dresden, which is cooperating with the IWS, treats the carbon film with electrons from the STM tips to create electrically conducting graphite dots in the isolating material. These tiny domains, less than 10 nanometers wide, are not only more conductive, they also project above the surface of the smooth film, explains Mühl and adds, Both effects can be used to store information. The STM needle serves as a combined write and read instrument, albeit a slow one. The high mechanical, thermal and chemical stability of carbon ensures that the data can be safely stored for long periods of time. Besides digital data, the researchers are looking at the possibility of storing and retrieving analog images. This is of particularly interest for long-term archiving since the method does not require digital conversion programs, which may one day become outdated or not even be available any more. A vivid example of the potential is a portrait photograph just 1.2 micrometers wide. By purely mathematical calculation, 6.2 billion such passport photos the entire human population would fit on the surface of a postcard. In the lingo of the data storage developer, this equates to a storage density of over 5,000 gigabits per square inch. Todays top magnetic hard drives achieve two percent of this value; commercially available drives a mere one percent. The two institutes are working together with Fraunhofer spin-off Arc Precision GmbH to transform the concept into a workable storage technology.For further information:,Thomas Muhl,Tel: +49 3 51 / 46 59-496,Fax: +49 3 51 / 46 59-7 45,E-mail: Dr. Bernd Schultrich,Tel: +49 3 51 / 25 83-4 03,Fax: +49 3 51 / 25 83- 3 00,E-mail: