2003/01/24 by J. M. North, D. Zipse, Naresh S. Dalal +7
Chemistry · Materials Science · Physics and Astronomy · #Absorption edge #Analytical Chemistry (journal) #Band gap #Chemistry #Condensed matter physics #Crystallography #Electrical resistivity and conductivity #Energy (signal processing) #Lanthanide and Transition Metal Complexes #Magnetism in coordination complexes #Materials science #Optics #Optoelectronics #Organic and Molecular Conductors Research #Photoconductivity #Photon #Photon energy #Physics #Semiconductor #cond-mat
paper · pdf · doi:10.1103/physrevb.67.174407
7 pages, 8 figures
arxiv created 2003/01/24 · openalex publication_date 2003/05/13 · arxiv updated 2009/11/30 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
Resistivity measurements are reported for single crystals of Mn12-acetate and Fe8Br8. Both materials exhibit a semiconductor-like, thermally activated behavior over the 200--300 K range. The activation energy Ea obtained for Mn12-acetate was 0.37\ifmmode±\else\textpm\fi0.05eV, which is to be contrasted with the value of 0.55 eV deduced from the earlier reported absorption edge measurements and the range of 0.3--1 eV from intramolecular density of states calculations, assuming 2Ea=Eg, the optical band gap. For Fe8Br8, Ea was measured as 0.73\ifmmode±\else\textpm\fi0.1eV, and is discussed in light of the available approximate band structure calculations. Some plausible pathways are indicated based on the crystal structures of both lattices. For Mn12-acetate, we also measured photoconductivity in the visible range; the conductivity increased by a factor of about 8 on increasing the photon energy from 632.8 nm (red) to 488 nm (blue). X-ray irradiation increased the resistivity, but Ea was insensitive to exposure.