MOLNANOMAG: Molecular nanomagnets

• Research unit: EU RFP
• Project number: 99.0792-1

Key words (English)

Molecular magnetism; spin clusters; single - molecule magnets

Alternative project number (English)

EU project number: HPRNCT1999-00012

Research programs (English)

EU-programme: 5. Frame Research Programme - 4.1.1 Research training networks

Short description (English)

See abstract

Further information (English)

Full name of research-institution/enterprise:
Universität Bern
Departement für Chemie und Biochemie

Partners and International Organizations (English)

Coordinator: INSTM, Florence (I)

Abstract (English)

The area of molecular magnetism is a very active area of transdisciplinary research including chemistry and physics. The so called 'Single molecule magnets' are the smallest known units capable of magnetically storing a bit of information. So far this is restricted to extremely low temperatures in the range of a few Kelvin.
We contribute in two areas to the joint European Network effort. Citrate has proved to be a very versatile ligand for the synthesis of spin clusters. So far a (Ni2+)7, two (Ni2+)8 as well as two (Ni2+)21 clusters have been prepared and magnetically characterized. The Ni21 clusters are of particular interest both structurally and magnetically. They contain an inner Ni7 core of Ni(OH)2 and thus constitute the first species created in the precipitation process of Ni(OH)2 at high pH. Below 1K the Ni21 clusters exhibit the slow magnetic relaxation behavior typical of single molecule magnets. The first (Co2+)8 cluster with citrate ligands has very recently been synthesized and magnetically characterized. A new synthetic program using a selection of Schiff-base ligands has led to two (Fe3+)3 clusters, two (Mn3+)4 and a (Ni2+)4 cluster. They are presently being investigated by magnetization measurements and inelastic neutron scattering (INS).
High resolution INS experiments have been performed on a number of materials, both synthesized in house and provided by other synthetic groups as part of a collaboration. These experiments are carried out at the PSI in Villigen, the ILL in Grenoble, the HMI in Berlin and the ISIS facility at the Rutherford labs in England. The most conclusive experiment was performed on a Mn4 single molecule magnet provided by the group of G. Christou in Florida. INS allowed an unambiguous and direct determination of the anisotropy interactions responsible for the single molecule magnet behavior.

References in databases (English)

Swiss Database: Euro-DB of the
State Secretariat for Education and Research
Hallwylstrasse 4
CH-3003 Berne, Switzerland
Tel. [phone]
Swiss Project-Number: 99.0792-1