Julia A. Thompson

A Molecular Ferromagnet with a Curie Temperature of 6.2 Kelvin: [Mn(C5(CH3)5)2]+[TCNQ]-.

The study of magnetic phase transitions in insulating molecular solids provides new insights into mechanisms of magnetic coupling in the solid state and into critical phenomena associated with these transitions. Only a few such materials are known to display cooperative magnetic properties. The use of high-spin molecular components would enhance intermolecular spin-spin interactions and thus a series of chargetransfer (CT) salts have been synthesized that utilize the spin S = 1 molecular cation, [Mn(C5(CH3)5)2]+ (decamethylmanganocenium). The structure and cooperative magnetic behavior of [Mn(C5(CH3)5)2]+[TCNQ- (decamethylmanganocenium 7,7,8,8-tetracyano-p-quinodimethanide) are reported. This salt is a bulk molecular ferromagnet with the highest critical (Curie) temperature (Tc = 6.2 K) and coercive field (3.6 x 103 gauss), yet reported for such a material.

Electronic properties of Ni(Pc)I under pressure

Abstract With a dramatic development of a single crystal growth technique for high purity, high quality nickel phthalocyanine iodide, Ni(Pc)I, we examined th e temperature dependence of the resistivity between 0.9–300 K under pressures between 3 and 14.5 kbar. We found a clear metallic temperature dependence in resistance at all pressures and an insulating phase at low pressures accompanied by a strong non-linear conduction. The conductivity at low temperature exceeded 45,000 S/cm at 14.5 kbar, which is already 7 times higher than the necessary condition to obtain superconductivity in β-(BEDT-TTF) 2 X salts.

Low temperature properties of Ni(Pe)I under pressure

Abstract In the previous ICSM, we presented a metal-insulator transition below 30 K accompanied by non-linear V - I characteristics. Although, the properties of metallic phase was completely reproducible, the samples in the present study showed no non-linear behavior. The M-I transition temperatures and pressures were also very much reduced. Since the conductivity is quite large at low temperature, superconductivity is still expected.