Single molecule magnets are promising candidates for performing data storage at the molecular level, due to their stable magnetization. The stability of the magnetization increases with increasing spin of the molecule and with increasing magnetic anisotropy. However, increasing spin leads to decreasing anisotropy and thus the magnetization does not become more stable. Manipulating directly the magnetic anisotropy through rational chemical design of single molecule magnets is extremely challenging.
PhD student Margarethe van der Meer (Berlin) prepared the fully air- and moisture stable compound. She says, "I was looking to make larger molecules with more metal ions, but I was fascinated to learn that even smaller molecules work just as well!" The in-depth investigation by PhD student Yvonne Rechkemmer (Stuttgart) led to a full understanding of why this molecule has such favorable properties. "It is one thing to find an interesting material by accident, it is quite another to be able to formulate clear design principles for even better materials," she says. The state of the art calculations by Professor Atanasov clarified exactly how the molecular structure is related to the magnetic stability. The next step is now to further improve the material in order to increase the operating temperature of the system. Professor Sarkar says, "We have plenty of ideas of how to improve the material further, now that we understand where its properties come from."
The work was financially supported by the Deutsche Forschungsgemeinschaft (DFG) and the Max Planck Society
Impression of how molecules might be incorporated in next-generation hard drives, with the structure of the molecule (top left), the magnetic hysteresis curve (top right) and the energy barrier between up and down orientation of the magnetic moment. (The image is free for media to publish provided the copyright holder is named: © Professor Joris von Slageren, Universität Stuttgart)