Kontrolliertes Wachstum von organischen Magneten auf hochgeordneten Isolator-Oberflächen
Zusammenfassung der Projektergebnisse
"Classical magnets" are usually metals or rare earth alloys, on the contrary, purely organicbased magnets are permanent magnets with s or p magnetic orbitals, combing the typical characteristics of organic molecules, such as chemical flexibility, ease of preparation, and structural design, with magnetism. We addressed the growth of highly oriented layers down to the sub-monolayer regime (thinner than 1/10 of the diameter of spider silk) on a substrate. We studied the ability of the molecules to order on a substrate, influences of substrate-molecule and molecule-molecule interaction on the magnetic properties, by using soft X-ray techniques and additionally techniques like atomic force microscopy. This idea was based on a new approach toward organic magnets. Nowadays, the importance of organic-based magnets is rapidly growing in view of their applications in electronics. What happens with the spin (the angular momentum carried by the unpaired electron of the radical) between a purely organic magnet and an inorganic substrate is largely unknown, because very few studies have been carried out on this class of interfaces, although this is a crucial aspect in a spintronics device. We shed light on the mechanisms occurring at the spinterface (the interface including the spin information) between the rutile titanium dioxide single crystal surface and a pyrenebased nitronyl nitroxide carrying a spin. We explored the role of defects on an organic spin at the interface: when the molecules interact with a defect site, the reactivity of the defect leads to chemisorption of the molecule, quenching its magnetic moment. Our work elucidates for the first time the crucial role played by the surface defects. This is a result of paramount and general importance ranging from chemistry to physics, from materials science to device physics. Ours is, thus, a powerful approach to understand the mechanisms governing complex interfaces, where it is important to describe both charge and spin behaviour. Our contribution to organic spinterface science (that was still in its embryonic phase when we submitted our proposal and it is still a very young and unexplored field) has been a pleasant surprise working on this project. Our first paper on purely organic magnets attracted lot of attention and I was contacted worldwide for several press releases (see for example, http://phys.org/news/2013-03-magnets-thin. html), and contributions an various media: 25 March 2013: pro-physik.de, “Organische Magnete in dünnem Film” (http://www.prophysik.de/details/vipnews/4529231/Organische_Magnete_in_duennem_Film.html) June/July 2013: Chemie Plus, Chemische Rundschau, page 24-25, article, “Nitronyl-Nitroxid_radikale für organische Magnete” (https://issuu.com/hk-gt/docs/_06-07_ganzes_heft_lo). Also our paper on the mark of surface defects on a spinterface gained a lot of attention with a press release at phys.org, “Defects at the spinterface disrupt transmission”, (http://phys.org/news/2016-09-defects-spinterface-disrupttransmission.html?utm_source=menu& utm_medium=link&utm_campaign=item-menu) and several contributions on the web, as for example, on 23 September 2016: New Electronics, article, “Research into defects at 'spinterface' could enable new applications” (http://www.newelectronics.co.uk/electronics-news/research-into-defects-at-spinterfacecould-enable-new-applications/146053/). This paper has an Altmetric Attention Score of 67. It is in the top 5% of all research outputs ever tracked by Altmetric (last access on 16.01.2017).
