Organic molecules allow producing printable electronics and solar cells with extraordinary properties. In spintronics, too, molecules open up the unexpected possibility of controlling the magnetism of materials and, thus, the spin of the flowing electrons. According to what is reported in ("Exchange bias and room-temperature magnetic order in molecular layers") by a German-French team of researchers, a thin layer of organic molecules can stabilize the magnetic orientation of a cobalt surface. 
The magnetic moments of the three organic molecules and the cobalt surface align very stably relative to each other. (Image: M. Gruber, KIT) “This special interaction between organic molecules and metal surfaces could help to manufacture information storage systems in a more simple, flexible and cheaper way,” explains Wulf Wulfhekel from KIT. Microscopic magnets with constant orientation are used in hard disks, for example. With a view to “printable electronics”, organic molecules indeed could open up new simple production methods utilizing the self-organization of molecules. In the present study, three molecular layers of the dye phtalocynine were applied to the surface of ferromagnetic cobalt. Whereas the magnetic moments of the molecules alternatingly align relative to the cobalt and relative to each other, the molecules form a so-called antiferromagnetic arrangement. The magnetic orientation of this combination of antiferromagnetic and ferromagnetic materials remains relatively stable even in the presence of external magnetic fields or cooling. “Surprisingly, the “lightweight” molecule wins this magnetic arm wrestling with the “heavyweight” ferromagnetic material and determines the respective properties,” Wulfhekel says. Systems of antiferromagnetic and ferromagnetic materials, among others, are used in hard disk reading heads. So far, manufacturing of antiferromagnets has been quite complex and time-consuming. Should molecules be suitable for use in the production, the antiferromagnets one day will simply come out of the printer. The present publication is the result of a cooperation of researchers from KIT, University of Strasbourg, and Synchrotron SOLEIL. First author Manfred Gruber was member of the German-French Graduate School “Hybrid Organic- Inorganic Nanostructures and Molecular Electronics”, where different aspects of nanoelectronics, spintronics, and organic electronics are investigated.
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The magnetic moments of the three organic molecules and the cobalt surface align very stably relative to each other. (Image: M. Gruber, KIT) “This special interaction between organic molecules and metal surfaces could help to manufacture information storage systems in a more simple, flexible and cheaper way,” explains Wulf Wulfhekel from KIT. Microscopic magnets with constant orientation are used in hard disks, for example. With a view to “printable electronics”, organic molecules indeed could open up new simple production methods utilizing the self-organization of molecules. In the present study, three molecular layers of the dye phtalocynine were applied to the surface of ferromagnetic cobalt. Whereas the magnetic moments of the molecules alternatingly align relative to the cobalt and relative to each other, the molecules form a so-called antiferromagnetic arrangement. The magnetic orientation of this combination of antiferromagnetic and ferromagnetic materials remains relatively stable even in the presence of external magnetic fields or cooling. “Surprisingly, the “lightweight” molecule wins this magnetic arm wrestling with the “heavyweight” ferromagnetic material and determines the respective properties,” Wulfhekel says. Systems of antiferromagnetic and ferromagnetic materials, among others, are used in hard disk reading heads. So far, manufacturing of antiferromagnets has been quite complex and time-consuming. Should molecules be suitable for use in the production, the antiferromagnets one day will simply come out of the printer. The present publication is the result of a cooperation of researchers from KIT, University of Strasbourg, and Synchrotron SOLEIL. First author Manfred Gruber was member of the German-French Graduate School “Hybrid Organic- Inorganic Nanostructures and Molecular Electronics”, where different aspects of nanoelectronics, spintronics, and organic electronics are investigated.
The TQ1 fibres (red) with live embryonic chicken cardiomyocytes growing on it (green). Being able to replace damaged organs and tissue with new tissue grown from cells from the recipient’s own body is one of the goals of regenerative medicine. The research has come a long way; today, for example, people who have suffered serious burns can have their body’s own skin grown. It is also known that cells grow better if they have some kind of support material, and several such materials have been tested. Daniel Aili, senior lecturer at the Division of Molecular Physics at LiU, and doctoral student Abeni Wickham, together with their research colleagues, have now succeeded in developing a support material with very special properties: “The material, a semiconducting polymer called TQ1, was initially developed for organic solar cells. But we have managed to process it to be a micro-fibrous material, like a mat of fibres where we can both study and stimulate the growth of tissue,” says Dr Aili. The material has a number of crucial benefits: “What’s interesting about it is that the cells seem to like the material and that it integrates well into living tissue. On top of that the fibres are fluorescent and glow in a wavelength range where we can see and follow the implant in the tissue. Until now, there has been a problem with soft biomaterials in that we have not been able to see how they integrate with living cells and tissue, and what happens with the material over time.” The researchers have also placed implants of spun TQ1 fibre in rats to be able to investigate the long-term effects. There have been no inflammations or other negative effects and the material has even shown that it can stimulate the growth of blood vessels in the tissue, which is a condition for the newly cultivated tissue to be able to be oxygenated and survive. The fluorescent properties of the material make it possible to follow its interaction with the tissue for as long as 90 days. Animal experiments are strictly regulated and the research has passed reviews both for ethics and for animal rights. The findings are a collaboration between six researchers from three divisions within the Department of Physics, Chemistry, and Biology at LiU; researchers from the Department of Clinical and Experimental Medicine at LiU; researchers at the Region Östergötland University Hospital; and one Chalmers researcher; Daniel Aili is the lead author.
Schematic illustration of single molecule-junctions consisting stacks of aromatic molecules in a self-assembled cage and the corresponding electronic components of the junctions. The assembled cage is sandwiched by two Au electrodes. Empty cage (a), homo-stacks and hetero-stacked pair (c) develop functions of resistor, wire and diode, respectively. Both identical and different modular aromatic pairs are non-covalently bound and stacked within the molecular scaffold leading to a variety of fascinating electronic functions. The empty cage presents a low electronic conductance (10