fields could speed storage
Technology Research News
Atoms 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
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
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,"
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'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
TRN Categories: Data Storage Technology; Materials Science
Story Type: News
Related Elements: Technical paper, "Observation of Coupled
Magnetic and Electric Domains," Nature, October 24, 2002.
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