Projet ANR-07-JCJC-0045 – fdp magnets : fdp magnets
Programme : Jeunes chercheuses & jeunes chercheurs (JCJC) 2007
Année de financement : 2007
Coordinateur du projet : ECOLE NORMALE SUPERIEURE DE LYON (ECOLE NORMALE SUPERIEURE DE LYON)
Partenaires : École normale supérieure de Lyon
Montant : 132000.0 euros
Date de début : 2007
Durée : 36 mois
Résumé : Tremendous amount of work on molecular-based magnets has been reported in the literature. -  Such magnetic compounds and particularly zero-dimensional clusters (so-called Single Molecule -  Magnets, SMMs) are currently subjects to spectacular interest since original magnetic materials -  with high-density information storage potential can be anticipated. Different strategies along with -  flourishing experimental techniques have been developed to investigate the unusual physical -  properties of these magnetic molecules and nanowires (Single Chain Magnets, SCMs). Even -  though these systems are not strictly 3D ordered compounds, the presence of hysterisis loop -  below a blocking temperature is a reminiscence of classical magnets. -  With this goal in mind, different synthetic routes -  have been considered and are currently subject to intense work. -  A detailed understanding of the magnetic phenomena in sophisticated -  architectures becomes rapidly unreachable since different subtle mechanisms are likely to -  compete. The traditional rationalization proceeds through the use of the well-known Heisenberg -  Hamiltonian which introduces effective magnetic coupling constants J. A more sophisticated -  approach calls for the participation of anisotropic contributions D and E in a generalized picture. -  Even though these phenomenological treatments have turned out to be extremely valuable in a -  comprehensive analysis of experimental data, the underlying physical phenomena still deserve -  special attention. In particular, how much the respective exchange and anisotropy terms have the -  ability to account for such intricate interactions is questionable. Besides, to what extent bridging -  ligands remain diamagnetic (innocent) as magnetic interactions between metallic centres are -  turned on. Even if such partitioning between physical effects and within magnetic moieties may -  not be straightforward, one can think of promising synthetic routes of magnetic systems. -  The fdp magnets project we plan to pursue relies on complementary experimental and -  theoretical skills. Considering the growing interest for 4f-based materials and their potential -  applications, there is a real need for theoretical analysis. Even though some methodologies and -  phenomenological approaches are available, DFT as well as ab initio techniques would be -  extremely insightful in the understanding of heavy-elements magnetic properties. Our project -  combines the synthesis of original and well-characterized prototype objects and the -  implementation of demanding calculations. Some architectures of ours are already available for -  theoretical inspection. However, specific objects which should hold controlled magnetic -  interactions will be prepared in the future to get a thorough understanding of the microscopic -  interactions. The association of f, d and p spin carriers within the same molecular objects is a -  challenging synthetic target, while understanding their physico-chemistry and more specifically -  their magnetic properties is an attractive theoretical problem. -                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              ...