| AVS 56th International Symposium & Exhibition | |
| Magnetic Interfaces and Nanostructures | Friday Sessions |
| Session MI-FrM |
| Session: | Molecular/Organic Based Magnetism |
| Presenter: | K.I. Pokhodnya, North Dakota State University |
| Authors: | K.I. Pokhodnya, North Dakota State University C. Olson, North Dakota State University A. Midgley, University of Missouri - Kansas City M.B. Kruger, University of Missouri - Kansas City A.N. Caruso, University of Missouri - Kansas City |
| Correspondent: | Click to Email |
M-TCNE molecule-based ferrimagnets demonstrate high magnetic ordering temperatures up to 400 K (M = V) due to strong AFM exchange between d-electrons of the metal and the anion-radical spin of the TCNE ligand. Magnetic and optical properties of the family of molecule-based 2D magnets [M(TCNE)(NCMe)2] X (M=Fe, Mn, Ni; X=BPh4, FeCl4, SbF6) will be discussed. Classical bonding-sensitive IR spectroscopy has difficulties distinguishing between the bonding and backbonding interactions (possibly mediating the strong superexchange), since their effects on CN bond stretching mode frequencies may cancel each other. In contrast, Raman active n(C=C) modes solely depend on charge transfer to/from the p* antibonding orbital, and thus are only backbonding sensitive. The observed strengthening of the n(C=C) and n(NºC) Raman modes for the compounds with higher Tc suggests the depopulation of the p* orbital and enhanced ligand to metal charge transfer resulting in a hybrid M3d-CN ground state with substantial admixture of ligand electron. The observed pressure-induced strengthening of the n(C=C) and n(NºC) Raman modes is in accord with proposed backbonding model. The correlation between the frequency shift (degree of backbonding) and magnitude of Tc from M(T) is established.