Metamagnetic transition and its related magnetocapacitance effect in phthalocyanine-molecular conductor exhibiting giant magnetoresistance

The magnetization and transport properties of iron-phthalocyanine molecular conductors are investigated under pulsed high magnetic fields up to 55 T. The metamagnetic transition is observed at approximately 14 T, where conductivity is enhanced. Below this transition, the tan S (= ∈"/∈') in the dielectric constants shows a monotonic decrease as the magnetic field strength increases, indicating that the magnetic field stabilizes the charge order. On the verge of this transition, the dielectric constants show a hysteresis below the weak-ferromagnetic transition temperature (6 K), suggesting that the π-electron charge order contributes to the weak ferromagnetism.