VoLuRad – Single-molecule magnets based on the orbitally-degenerate spin centers and stable organic radicals complexes

Fiche  technique du Projet

• Programme de financement: 7e PCRD – programme Personnes  – Marie Curie Actions -  International Incoming Fellowships (IIF)
• Coordinateur: Université Claude Bernard Lyon 1, Prof. Dominique Luneau
• Budget Total: € 269.096,40
• Subvention : € 269.096,40
• Durée : 23/07/2012-22/07/2014


Context / Contexte

Molecular magnets may be organized into two classes. One class comprises the so-called moleculebased magnets (MBM) in which the spin carriers interact in a three-dimensional array in the solid state. They may be organic, organometallic or coordination compounds. The second class concerns the socalled single-molecule magnets (SMM) in which a limited number of metal ions form a large molecule with a large magnetic spin. The magnetism, in this case, is fundamentally different from the traditional magnets and no longer a bulk property. Indeed, such molecules behave individually as magnets and exhibit “quantum properties” such as the Quantum Tunneling of Magnetization (QTM) effect. SMM have been proven to be relevant for quantum computing but the blocking (operating) temperatures below which these phenomena are observed are still too low (<9K) for applications.
The first SMM to be discovered was “[Mn12],” a Mn8IIIMn4IV mixed-valence compound of formula [Mn12O12(O2CCH3)16(H2O)4] that has a ground spin state of S=10 and negative magnetic anisotropy D=-0.5cm-1. This resulted in a spin reversal barrier of approximately 50cm-1 and magnetic blocking temperature below 4K. Only recently has magnetisation blocking been increased to 8.3 K in a [Dy(N2)3-Dy] binuclear complex. Obviously, there are formidable challenges in both chemistry and physics to understand how to increase both the temperature and the lifetime of the observable effects.
The societal advantages of molecular magnets are numerous. Since its discovery a century ago, magnetic recording has revolutionized our lives from in media and in computing. The aim of molecular magnets is not to replace the existing magnets but to have novel magnetic materials for future applications in information processing and storage. For example, SMM may increase storage density 10000 times compared to current devices.6 In contrast to traditional magnets, they are mainly organic with a small fraction of inorganic metal centres. Some are even purely organic. This gives properties, which do not exist in traditional magnets such as low density, transparency, flexibility and colour. Thanks to their organic moieties they may be functionalized to be grafted onto surfaces or to make them biocompatible for example. SMM are mono-disperse and soluble in organic solvents in contrast to magnetic particles. As they are made under mild conditions, molecular magnets are energy-saving and their environmental impact might be low. In addition, they are well-suited for multi-property purposes. For example, magnetism may be combined with optical properties in order to have magneto-optic information storage or with conductivity for spintronics applications. Other possibilities concern sensors and switches.

Objectives / objectifs

The objectives of the project are to gain new and fundamental knowledge in chemistry as well as physics of SMMs in order to increase blocking temperatures.

Impact/ results – Impact/résultats

Magnets as support to information storage and process are central in our modern life. In a next future higher storage densities will be needed that are not attainable using conventional technologies. A Molecular approach to this problem seems to be appropriate. This approach was proposed in the eighty’s by pioneers so that the field is well developed in Europe which has still the leadership in this field. However, there is a strong competition with teams in USA, Japan and China.
In Russia, research is now reorganised and laboratories, such as the Institute of Inorganic Chemistry obtain sound results. It is our opinion that these cleaver researchers are entitled to collaborate with European teams for mutual benefit.

Le rôle de LIP 

LIP a accompagné le porteur de projet dans toute la phase de montage et de mise en place du contrat avec la Commission Européenne.