Magnetic Properties of FeCl₃-Graphite Compounds. I. Mössbauer Studies

Abstract

Magnetic properties of layered compounds of graphite, in which a FeCl₃ layer is separated by one (the 1st stage) or two layers (the 2nd stage) of graphite were studied by Mössbauer effect. The easy directions of spins were within the basal plane for the both stages, which were determined by measuring relative intensities of Zeeman components on samples of well orientated c-axis. The temperature dependence of internal magnetic fields could be described according to the Weiss theory for S=5⁄2 normalized to H_n(0K)=500 kOe and with T_N=4 K. The coexistence of a central line and Zeeman lines, and their temperature dependent intensities could be interpreted as the superparamagnetic system with clusters of one molecular thickness and mean diameter ≈1000 Å. The observed quadrupole splittings 0.20 mm/sec for the 1st stage and 0.25 mm/sec for the 2nd stage were considered as due to trigonal distortions from the regular octahedrons of FeCl₃ molecule.