Dresden 2020 – wissenschaftliches Programm
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TT 63.9: Vortrag
Donnerstag, 19. März 2020, 17:30–17:45, HSZ 304
Chemical design strategies and field-induced phases in antiferromagnetically coupled organic spin-dimer systems — •Bernd Wolf1, Lars Postulka1, Paul Eibisch1, Ulrich Tutsch1, Martin Baumgarten2, and Michael Lang1 — 1Physics Institute, Goethe-University, SFB/TR49, D-60438 Frankfurt (M) — 2Max-Planck-Institute for Polymer Research, SFB/TR49, D-55128 Mainz
Coupled antiferromagnetic spin-dimer systems based on the stable organic radical units nitronyl-nitroxide (NN) and imino-nitroxide (IN) are recognized as suitable candidates for exploring critical phenomena under well-controlled conditions. For these systems the intra- and inter-dimer magnetic exchange interactions can be modified in specific ways. Depending on the geometry of the inter-dimer couplings, various scenarios can be observed. We discuss the magneto-structural correlations of selected materials based on tolan molecules linked together with NN- and IN-units. Furthermore, using low-temperature ac susceptibility and specific heat measurements we characterize the field-induced magnetic phases of these materials and discuss their critical behavior. In addition, we present a new approach for designing inter-molecular magnetic exchange interactions based on planar π-bridges of benzo[1,2 -b:4,5 -b’] dithiophene derivatives which connect the stable NN and IN radical units. Our results demonstrate that π-stacking of the planar bridges allows a good control of the inter-molecular magnetic exchange.