Aligned
fields could speed storage
By
Kimberly Patch,
Technology Research NewsAtoms are like tiny magnets, with poles that repel each other. The opposite ends of atoms also have opposite electrical charges. When the atoms or molecules within a material line up, the material as a whole has magnetic or electric poles.
Today's electronic devices use just one of the two orientations. Magnetic computer disks, for instance, represent the ones and zeros of digital information using the magnetic orientations of tiny areas, or bits, of a material, while computer memory chips only use electric orientations.
This could change. Researchers from three institutes in Germany and Russia have found a material whose electric and magnetic domains line up together. The work could bring together the currently separate fields of magnetic and electronic data storage, which would give both methods more flexibility.
The researchers discovered the phenomenon after finding it was possible to image the magnetic and electric domains of a material at the same time by bouncing light waves off the materials, then making an image of the way both the magnetic and electric fields of the material changed the light waves' phases. "It works similar to holography," said Manfred Fiebig, a scientist at Dortmund University and at the Max-Born Institute in Germany. It "allows us to tell the difference between the very similar electric and magnetic domains in our... samples and image them as bright and dark areas," he said.
The results showed that the magnetic and electric domains in the material yttrium manganese oxide lined up. "The surprising result was the discovery of the very strong [alignment] of electric and magnetic domains," said Fiebig. This is something that had not been observed before, he said.
Materials like these may eventually make it possible to write data to a device using one method and read it using another, said Fiebig. It could, for instance, enable faster methods of storing information on magneto-optical disks by changing the magnetization using electrical properties, he said.
Coupled magnetic and electric devices could also find applications in spintronics, said Fiebig. Spintronics uses the magnetic orientations of electrons to control the flow of electric current. The electric writing and magnetic reading could be used in these devices, he said.
The method required that the measurements take place at a very low temperature, which meant devising a way to rotate the sample inside a cryostat -- "a high-end thermos bottle with windows," said Fiebig. And to image the electric properties of the material, the researchers had to make the measurements while the material was in the electric field. To apply this field, the researchers used transparent electrodes that did not interfere with the lasers.
Properties of pieces of material as small as one nanometer can be measured this way. A nanometer is a millionth of a millimeter, or the span of 10 hydrogen atoms.
Practical developments will require finding new compounds that show the linked properties at higher temperatures, Fiebig added. "The key question is the development of other ferroelectromagnetic materials which are more favorable for technical applications, meaning higher magnetic ordering temperatures, [and] easy control of the magnetic and electric state," he said.
The research is intriguing, said Anthony Bland, a professor of physics at the University of Cambridge in England. The effects "may be useful in as yet unforeseen ways," he said.
Finding uses for this type of material is a long way off, however, Bland said. First, similar materials that can be used at higher temperatures would have to be found. "These experiments were conducted at very low temperatures whereas real devices will require a room-temperature operation. This is likely to be a very challenging materials problem," he said.
In addition, the method is very unlike the general body of current research on materials for uses like storage. Eventual applications would be based on a new methodology which is not yet proven, he said.
The researchers are working to show control of the electric state of the material using its magnetic field and control of the magnetic state of material using its electric field, Fiebig said. They are also working on a theoretical explanation of the mechanism involved, he said.
The researchers are also looking to expand the imaging method to clarify unknown magnetic and crystallographic structures as an alternative to the classical diffraction techniques involving neutrons, x-rays, and electrons, Fiebig said.
Fiebig's research colleagues were Thomas Lottermoser and Dietmar Froehlich at Dortmund University in Germany, and Alexander V. Goltsev and Roman V. Pisarev from the Ioffe Physical Technical Institute of the Russian Academy of Sciences. They published the research in the October 24, 2002 issue of Nature. The research was funded by the German research Council (DFG) and the Russian Foundation for Basic Research.
Timeline: 10 years
Funding: Government
TRN Categories: Data Storage Technology; Materials Science and Engineering
Story Type: News
Related Elements: Technical paper, "Observation of Coupled Magnetic and Electric Domains," Nature, October 24, 2002.
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January 1/8, 2003
Page One
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Altered protein orders metal bits
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Electron pairs power quantum plan
Aligned fields could speed storage
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