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The “Magnetism of Nanoscopic
Systems” team at the Louis Néel Laboratory studies magnets
that are ever-smaller in size, down to the molecular scale. Molecular
magnetism makes it possible to store magnetic information on a single
molecule and could tremendously increase the capacities of computers.
The team has successfully controlled the magnetic behavior of a dimer
of molecular magnets interacting according to the subtle laws of quantum
mechanics, which may pave the way for applications for the quantum processing
of information.
It was shown recently that
individual molecules may behave like nanoscale magnets. Each molecule,
whose behavior may be compared to that of a compass, can be blocked in
a given direction by a magnetic field, below its “blocking temperature.”
Such stability guarantees that the information provided by the magnetic
field will be stored and can be retrieved at a later time.
At the molecular scale, however, a purely quantum phenomenon, the "tunnel
effect," can alter the magnetization of molecules. This effect, which
is impossible according to the laws of classical physics, represents a
disadvantage for information storage, where the movement can lead to the
loss of the orientation that was meant to be blocked and, therefore, to
information loss. The researchers on the “Magnetism of Nanoscopic
Systems” team decided, on the contrary, to make use of this effect
by controlling it in order to develop “quantum devices” that
operate based on a different principle, taking advantage of these surprising
effects to imagine new types of information storage and processing at
this scale.
They developed and studied a first example of two molecular magnets coupled
“antiferromagnetically,” which tends to orient the two magnets
in opposite directions. Each magnet influences its neighbor; therefore,
the quantum behavior of the single-molecule magnet dimer is different
from that of the individual single-molecule magnet. This study, which
was published in the March 28, 2002 issue of Nature, shows that
it is possible to fine-tune the quantum properties of molecular magnets,
which represents a crucial step for future applications in the field of
quantum processing of information.
This work was carried out in close collaboration with researchers in the
chemistry laboratories of George Christou (University of Florida) and
David N. Hendrickson (University of California at San Diego), who synthesized
the molecules.
Reference
Exchange-biased quantum tunnelling in a supramolecular dimer of single-molecule
magnets, Wolfgang Wernsdorfer, Núria Aliaga-Alcalde, David N. Hendrickson,
George Christou, Nature, 416, 406 - 409 (28 March 2002).
Researcher
Contact:
Wolfgang Wernsdorfer
Tel: +33 4 76 88 79 09
E-mail: wernsdor@polycnrs-gre.fr
Press Contact:
Magali Sarazin
Tel: +33 1 44 96 46 06
E-mail: magali.sarazin@cnrs-dir.fr
Department of Physical Sciences and Mathematics
Communications Contact:
Frédérique Laubenheimer
Tel: +33 1 44 96 42 63
E-mail: Frederique.Laubenheimer@cnrs-dir.fr
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