The scientists' challenge was to find a suitable molecule as well as a suitable surface and to combine both with the right method. Magnetic molecules, so-called spin crossover molecules, are very sensitive and can be easily destroyed. The researchers therefore had to find a way to fix the molecule firmly on the surface and at the same time maintain its switching characteristic. The chemists from the research group led by Professor Felix Tuczek at the Institute of Inorganic Chemistry at CAU produced a magnetic molecule of a special class (a so-called iron (III) spin crossover molecule). This molecule could easily be bonded to a copper nitride surface by vapor deposition.
It is not only possible to switch between different spin states, but also (in the so-called "low spin" state) between two different orientations. The fine tip of a scanning tunneling microscope (RTM) performs the function of the read/write head in the hard disk. With its help, the molecule can not only be written to as a storage medium, but can also be read out via electricity. The principle applicability of the molecules as data storage devices was demonstrated with the aid of a scanning tunneling microscope. However, before these molecules can really be used as data storage devices for the industrial market, there is still an important hurdle to be overcome: it must be clarified how the molecules can be integrated into a chip.
The acehievement was published first the Nano Letters magazine under the title “Robust and Selective Switching of an Fe III Spin-Crossover Compound on Cu2N/Cu (100) with Memristance Behavior. Nano Letters 2017 17 (11), 6613-6619, DOI: 10.1021/acs. nanolett. 7b02481 ".