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Franck Balestro
Néel Institut, CNRS-UJF
NANOsciences Department
25 Av. des Martyrs, BP 166
38042 Grenoble cedex 9
France
[email protected]
+ 00 33 (0)4 76 88 79 15 office
+ 00 33 (0)4 76 88 74 41 lab
+ 00 33 (0)4 76 88 11 91 fax
I'm a physicist specializing in condensed-matter experiment, particularly spins of
electrons confined to submicron quantum dot structures. Some recent projects in the
group have investigated: Coulomb blockade effects, Spin-1/2 and Spin-1 Kondo effects
and quantum phase transition. I did my Ph. D. at the « Centre de Recherche sur les Très
Basses Températures » in Grenoble on the quantum dynamic of a DC-SQUID, leading
to the observation of macroscopic quantum tunneling and Rabi oscillations. I was then a
post doc at the Kavli institut in Delft, in the Quantum Transport group, and worked on the
detection of quantum noise using on-chip quantum detectors
N. Roch, S. Florens, V. Bouchiat, W. Wernsdorfer and F. Balestro
Néel Institut, CNRS, NANOsciences Department
Nanospintronic and Molecular Transport team.
Molecular Spintronics
A revolution in electronics is in view, with the comtemporary evolution of the two novel
disciplines, spintronics and molecular electronics. A fundamental link between these two fields
can be established using molecular magnetic materials and, in particular, single-molecule
magnets, which combine the classic macroscale properties of a magnet with the quantum
properties of a nanoscale entity. The resulting field, molecular spintronics [1] aims at
manipulating spins and charges in electronic devices containing one or more molecules. The
main advantage is that the weak spin-orbit and hyperfine interactions in organic molecules
suggest that spin-coherence may be preserved over time and distance much longer than in
conventional metals or semiconductors.
In this context, we are trying to fabricate, characterize and study molecular devices
(molecular spin-transistor [2], molecular spin-valve and spin filter, molecular double-dot devices,
carbon nanotube, nano-SQUIDs [3], etc.) in order to read and manipulate the spin states of the
single molecule device and to perform basic quantum operations. However, by decreasing the
size of a single quantum dot, interesting fundamental physics can be unvealed, like quantum
phase transition for example. Quantum criticality is the intriguing possibility offered by the laws of
quantum mechanics when the wave function of a manyparticle physical system is forced to
evolve continuously between two distinct, competing ground states. This phenomenon, often
related to a zero-temperature magnetic phase transition, can be observed in several strongly
correlated materials such as heavy fermion compounds or possibly high-temperature
superconductors. In contrast to these bulk materials with very complex electronic structure,
artificial nanoscale devices could offer a new and simpler vista to the comprehension of quantum
phase transitions. This long-sought possibility is demonstrated by our work in a fullerene
molecular junction, where gate voltage induces a crossing of singlet and triplet spin states at
zero magnetic field.
1 : L. Bogani & W. Wernsdorfer, Molecular spintronics using single-molecule magnets, Nature Mater., 7,
179-186 (2008)
2 : N. Roch, S. Florens, V. Bouchiat, W. Wernsdorfer & F. Balestro, Quantum phase transition in a singlemolecule quantum dot, Nature, 453, 633-637 (2008)
3 : J.-P. Cleuziou, W. Wernsdorfer, V. Bouchiat, T. Ondarçuhu & M. Monthioux, Carbon nanotube
superconducting quantum interference device, Nature Nanotech., 1, 53-59 (2006)