Dresden 2014 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 2: Symposium Magnetic/Organic Interfaces and Molecular Magnetism SYMO (MA jointly with CPP, DS, HL, O, TT)
O 2.3: Hauptvortrag
Montag, 31. März 2014, 10:45–11:15, HSZ 02
On-surface magnetochemistry of spin-bearing metalorganic molecules — •Peter M. Oppeneer1, Kartick Tarafder1, Ehesan Ali1, Nirmalya Ballav2, Christian Wäckerlin3, and Thomas A. Jung3 — 1Uppsala University, Uppsala, Sweden — 2IISER, Pune, India — 3PSI, Villigen, Switzerland
Planar spin-bearing metalorganic molecules such as metal-porphyrins and -phthalocyanines are paramagnetic in the gas phase, however an interface exchange coupling develops when these molecules are assembled on magnetic surfaces, which induces spontaneous molecular magnetic order at room temperature. To unveil fundamental origins of the exchange interaction leading to the metalorganic molecule/substrate spin-interface we use ab-initio DFT+U calculations with dispersion corrections added. Our calculations provide detailed, orbitally-resolved insight in the molecule-surface exchange interactions as well as the spin-switching induced by additional ligation in the free ligand position of the metal ion by small molecules such as NO and NH3. We find that on-surface coordination chemistry of planar metalorganic complexes gives rise to novel magnetochemical effects, which challenge the notions of classical coordination chemistry. A key to these magnetochemical effects is the weak bonding to the surface, i.e. a “surface" trans effect. Our calculations further reveal that certain systems, as e.g. Cu-phthalocyanine on Co, are liable to formation of novel spin-polarized interface states that are expected to be particularly suited for spin-polarized electron injection in metalorganic layers.