Magnetic properties of mixed graphite containing both hexagonal and rhombohedral forms
Centre de Recherche Paul Pascal, CNRS, avenue A. Schweitzer,
33600 Pessac, France
Revised: 28 April 1999
Published online: 15 January 2000
Magnetic properties of graphite materials containing variable fractional amounts (up to 40% ) of the Rhombohedral graphite form have been investigated by means of electron spin resonance. The variations with temperature and rhombohedral content of the Landé g-factor, ESR linewidth and paramagnetic spin-susceptibility have been analyzed. A narrow parallelism in the behaviours of the g-factor, linewidth and diamagnetic susceptibility (as the latter is known from an earlier work by Gasparoux) has been perceived, conforming to a similar parallelism between these three physical quantities present in earlier works on graphitic-type systems, but there, as a function of high-temperature-treatment and dopant concentration. From the g-value results, the g-anisotropy of the rhombohedral structure is inferred. The paramagnetic spin-susceptibility shows an increased tendency toward 2D character with increased rhombohedral content, in agreement with the theoretical predictions of McClure concerning (hypothetical) rhombohedral graphite.
PACS: 81.05.Tp – Fullerenes and related materials; diamond, graphite / 76.30.-v – Electron paramagnetic resonance and relaxation / 75.30.Gw – Magnetic anisotropy
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2000