| AVS 63rd International Symposium & Exhibition | |
| Magnetic Interfaces and Nanostructures | Tuesday Sessions |
| Session MI-TuA |
| Session: | Magnetic Phenomena in Organic Systems |
| Presenter: | Greg Szulczewski, The Univeristy of Alabama |
| Authors: | G.J. Szulczewski, The Univeristy of Alabama E. Ellingsworth, The Univeristy of Alabama |
| Correspondent: | Click to Email |
Spin-crossover in molecular complexes containing divalent Fe ions (six d-electrons) is a phenomena associated with a reversible change in the magnetic state (diamagnetic to paramagnetic and vice versa) as a function of temperature, pressure or optical excitation. In this study we demonstrate the growth of bis(1,10-phenanthroline)dithiocyanato iron (II) or Fe(phen)2(NCS)2 thin films, a well-known spin crossover material. A detailed SQUID magnetometry and spectroscopic analysis using Raman, IR, UV-Vis, and XPS, indicates that the as-deposited films are largely a diamagnetic compound that can be best described as Fe(phen)3(NSC)2. Upon annealing the films under high vacuum, the diamagnetic compound can be converted into a paramagnetic compound, which is consistent with the formation of Fe(phen)2(NCS)2. The annealed films are polycrystalline as revealed by x-ray diffraction and exhibit a spin-crossover transition near 180 K. The DC electrical conductivity of these films was measured from 100-300 K. A small (but repeatable) change in the electrical conductivity was observed. An unequivocal interpretation of this observation is difficult because of competing factors. For example, the unit cell expands across the spin-crossover transition, the geometric structure of the molecule changes, and the frontier molecular orbital energies also change. The relative contribution of these factors will be discussed in detail.