Molecular magnets of a new kind
Molecular magnets could become the components of tomorrow's quantum computing. Researchers at the Molecular Chemistry Laboratory have been involved in work that has led to a better understanding of thulium-based magnet molecules and to leads for the synthesis of more efficient molecular magnets.
Credit : Gregory Nocton
A new kind of organometallic lanthanide molecule has demonstrated remarkable magnetic properties: the more it is isolated, the more it tends to behave like a magnet, which is the opposite of the classical magnetic properties. This research was conducted by a collaboration of researchers from the Institut Polytechnique Paris, the Université Paris-Saclay and the Institut des Sciences Chimiques de Rennes of the Université de Rennes 1.
Discover more thanks to this translation of an article from the Institute of Chemistry of the CNRS
Molecular magnets, capable of magnetising in isolation, could have very important potential applications in high-density information storage, quantum computing or spintronics. As with all magnets, their magnetisation eventually disappears through magnetic relaxation. The slower the magnetisation disappears, the better the magnet, hence the importance of better understanding the phenomena that control this relaxation. Work carried out by teams from the Molecular Chemistry Laboratory (LCM*), the Institut de chimie physique (CNRS/Université Paris-Saclay) and the Institut des Sciences Chimiques de Rennes (CNRS/Université de Rennes 1) shows that, for a new thulium-based magnet molecule, the more isolated the molecules are from each other, the slower their magnetic relaxation. These results, published in the journal Angewandte Chemie, will enable the development of new synthesis strategies to move towards ever more efficient magnet molecules.
Magnets are omnipresent in our daily lives: they are found for example in electric motors, cars, computers, credit cards, telephones, refrigerators, etc. At the end of the 1990s, the first "magnet molecules" appeared and have since been the subject of much research for potential applications in spintronics.
A magnet is a system which, once magnetised by a magnetic field, retains this magnetisation in the absence of a field. This situation is known as metastable, which means that the magnetisation will eventually disappear (a phenomenon known as relaxation), but after a very long time. For example, the lifetime of information stored on a hard disk is of the order of a few decades. So the slower the magnetisation disappears, the better the magnet. It is therefore important to better understand the parameters that control this relaxation in order to orientate synthesis towards high-performance systems.
Hence the research carried out by scientists from the LCM and the Institut des Sciences Chimiques de Rennes on a new thulium-based 'sandwich' molecule (the thulium is found in the middle of two large organic molecules that mimic bread in a sandwich, see image). Beyond the synthetic feat that made it possible to obtain this system in which thulium is at a +2 oxidation state that is quite unusual for this atom, the teams were able to characterise the factors contributing to magnetic relaxation, such as the spin of the atomic nucleus or magnetic dilution. By modifying the close environment of this molecule, they showed that the more isolated the molecules were from each other, the slower their magnetic relaxation. These results, to be found in the journal Angewandte Chemie, will make it possible to develop new synthesis strategies to move towards ever more efficient magnet molecules.
> Read publication : https://doi.org/10.1002/ange.202015428
* LCM: a joint research unit CNRS, École Polytechnique - Institut Polytechnique de Paris