German researchers find new storage medium
- 27 May, 2007 22:00
Scientific researchers claim to have discovered a storage technology that could combine solid state size, speed and reliability with hard drive capacity but without spinning hard drive mechanisms. The technique is experimental and depends upon almost perfect material consistencies at the nanoscale level. Don’t sell your Seagate stock though; it isn’t going to happen any time soon.
Scientist Guido Meier at Germany’s University of Hamburg created tiny magnetised regions in a nanoscale wire made of an iron and nickel combination called Permalloy. The wire is less than a micro thick. Like any magnetic storage, the regions contain atoms oriented the same way to a magnetic pole. The edge of a region is termed a domain wall and, again like in any other storage medium, the presence or absence of a binary digit is signalled by the change at the domain wall from magnetised atoms oriented one way to another.
Meier’s team used soft X-ray microscopic techniques pioneered by Peter Fischer at the Lawrence Berkeley National Laboratory in California. Instead of detecting magnetic changes magnetically, X-ray microscopy was used to look at the domain walls — which are as small as 15 nanometers in length — and almost visually detect the atom’s orientation.
Because there is, on the one hand, a nanoscale wire holding a series of magnetised regions and, on the other hand, a single detector, the X-ray device, Meier’s team found a way of moving the magnetised regions along the wire by injecting nanosecond electronic pulses into it. These caused the magnetised regions to move along the wire at 110 metres per second and pass by the X-ray microscope, which could snap its images and read them.
Such X-ray microscopes would not be used if the technology was commercialised. They are far too complex, large and expensive and millions of them would be required.
IBM’s Almaden Research centre has a similar idea called a magnetic racetrack idea.
It involves a relatively long nanowire that has three sections: a stored magnetic zones and domain walls area; a read area with a read/write sensor to read/write magnetised areas; and a termination area where the magnetic zones and walls are stored after reading or writing.
A memory chip using this technology would have millions of U-shaped nano-scale wires and sensors built into it. IBM patented its concept in 2004. The effort stalled because actual speeds were much slower than scientific theory predicted. What Meier and his team have achieved is to speed up magnetic region movement along the wire a hundred-fold and to show that such a memory technology is now theoretically possible.
In a chip using this technology, each nanoscale wire would be read sequentially. That means, supposing you have an 8-bit wire, that you would need 8 billion of them to store 1GB of information, together with a billion read/write sensor heads.
Manufacturers would need to achieve very high purity in the nanoscale wires with relatively few atoms. Tolerances would be tiny. Any imperfections cause the speed of the magnetic regions along the wire to slow or stop altogether. Consequently, this research technology would present a massively parallel storage medium of great complexity in terms of manufacture and test if it was to be commercialised.
It will be a very hard manufacturing problem. To allow for imperfections in some nanowires, it would be necessary to over-provision a magnetic racetrack chip so that bad elements could be ignored. Depending upon the imperfection ratio, it would be necessary to over-provision by 10-20% and possibly more.
This idea is like bubble memory and similar revolutionary storage ideas that combine solid state’s speed, size and reliability with magnetic disc’s capacity but without hard drive’s mechanics. It may never happen — and remember, nanoscale researchers spin as much as hard drives when looking for scientific glory and research funds.
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