Utilizing techniques for synthesizing very pure M(pc), (pc=phthalocyanine), we prepared alloys of the type CuxM1-x(pc)I, M=H2 or Ni to examine the interaction between the conduction electrons and the local moments associated with the S=1/2CuII metal ions embedded in the macrocycle center. The effects of the local moments, which include large decreases in conductivity and large positive magnetoconductivities, are greatly enhanced in these purer materials. Introduction of 5% Cu(pc) reduces the conductivity by a factor of 3. This same alloy shows a positive magnetoconductivity with a relative increase in conductivity of tenfold; this effect is four times greater than that observed in Cu0.05Ni0.95(pc)I made from commercially available material. Magnetic studies including susceptibility and electron paramagnetic resonance confirm that the two spin systems are strongly coupled. A magnetic susceptibility fit to a Curie-Weiss expression yields a Weiss constant, ?, that increases linearly with x, the Cu content. The slope of ? is explained in the companion paper by Martin and Phillips [Phys. Rev. B 60, 530 (1999)].
|Original language||English (US)|
|Number of pages||7|
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|State||Published - 1999|
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics