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NEWS OF THE WEEK
NEW MATERIAL FOR
DATA STORAGE
MATERIALS SCIENCE: Spin-transition
compounds prove amenable
to nanoscale processing
AFAMILY OF COMPOUNDS endowed with a
property that enables them to be switched
between two magnetic states may form the
basis of future high-density data-storage technologies,
according to researchers in Italy and Germany. Their investigation
demonstrates that molecular spin-transition
compounds can be fashioned into robust micro- and
nanometer-scale structures for data-storage devices
(Angew. Chem. Int. Ed. 2008, 47, 8596).
In the push to increase the data-storage capacity of
electronic devices, manufacturers have steadily shrunk
the size of the elements that make up the patterns that
represent data. For magnetic hard drives in computers,
the “elements” are magnetic domains—microscopic
regions of the disk surface—which are magnetized during
the data-writing process in specific orientations.
Hard-drive manufacturers continue to pack more
information on disks by “writing smaller,” that is, by
shrinking the domains. But that approach, which has led
to today’s nanoscale domains, cannot be continued much
longer. Smaller domains are known to spontaneously lose
their magnetic orientation, which would lead to data loss.
Faced with that impending size limit, researchers
in various labs are pursuing alternative data-storage
strategies based on the properties of much smaller
entities—individual or small numbers of molecules.
Spin-transition (ST) compounds, such as those based
on Fe(II) species, have been proposed
as candidates for such applications because
their molecules can be triggered by
temperature and other stimuli to switch
between a diamagnetic (or low spin) and
a paramagnetic (or high spin) state.
Until now, however, only limited progress
has been made in developing methods
for processing these compounds and
“drawing” microscopic patterns with
them. In addition, some of those procedures
were found to adversely alter the
materials’ properties.
Now, Massimiliano Cavallini of the Institute of
Nanostructured Materials, in Bologna, Italy; Mario Ruben
of the Karlsruhe Research Center, in Germany; and
coworkers have shown that an Fe(II) phenanthroline
ST compound can be used to form well-ordered and
durable nanoscale patterns and that the material retains
its spin-flipping quality after processing.
Demonstrating the Fe(II) compound’s usefulness
as a nanoscale “ink,” the team employed lithographic
stamping methods to draw a replica of the data-storage
pattern encoded on a compact disc, which consists of
nanometer-thick dots and lines. On the basis of
microscopy, X-ray measurements, and Raman
spectroscopy, the team reports that after patterning,
the material is highly crystalline and can
be induced to switch between magnetic states by
altering the temperature.
“This is a nice piece of work,” says Daniel Ruiz-
Molina of the Center for Investigation in Nanoscience
& Nanotechnology, in Bellaterra, Spain.
In addition to advancing fundamental science,
“this pioneering work will open the door to the
development of a new generation of moleculebased
storage systems,” he says.—MITCH JACOBY
“Written” with an
Fe(II) “ink,” this
CD data pattern
features lines of
submicrometerscale
length and
width (blue, optical
micrograph) and
up to 80-nm height
(orange, AFM
image).
N
N
N
Fe
N
NCS
NCS
Fe(II) phenanthroline
MASSIMILIANO CAVALLINI/
INST. OF NANOSTRUCTURED MATERIALS
MERGERS AND ACQUISITIONS Banks balk at funding Hexion-Huntsman deal
Credit Suisse and Deutsche Bank have
scuttled Hexion Specialty Chemicals’
attempt to close its $10.6 billion acquisition
of Huntsman Corp. on Oct. 28.
The banks told the two companies
they would not provide the necessary
loans because they deemed the solvency
certificate provided by Huntsman Chief
Financial Officer J. Kimo Esplin and
the solvency opinion retained from the
independent financial evaluation firm
American Appraisal unsatisfactory. These
documents assert that the combined
company would be able to pay its debts.
Hexion has been seeking a way out of
the deal since June, when it filed suit in
the Delaware Court of Chancery arguing
that deterioration in Huntsman’s
performance would make the combined
companies insolvent. Huntsman won
court backing for the deal in September
in that suit and has also received rulings
in Texas against the two financing banks,
preventing them from filing suits alleging
insolvency.
By denying the financing, the banks
are rejecting the American Appraisal
opinion that the merged companies
would, as Huntsman has described it,
satisfy “solvency tests commonly used
in transactions of this nature.” Huntsman
points out that Credit Suisse has testified
that it would provide financing as
long as it received an “independent opinion
in which no reasonable lender, acting
in good faith, could object.”
Following the banks’ decision, Hexion
filed a lawsuit in New York City against
Deutsche Bank and Credit Suisse asking
the court to compel them to fund
the merger. “Both Hexion and Huntsman
are ready, willing, and able to complete
the merger immediately but have been
prevented from doing so by the banks’
breach,” Hexion CEO Craig O. Morrison
said in a statement.
Should the merger fail to close, Apollo
and the banks face a trial in Texas, set
to begin in February, in which Huntsman
is seeking more than $3 billion in
damages.—ALEX TULLO
WWW.CEN-ONLINE.ORG 11 NOVEMBER 3, 2008