Magnetothermal oscillations, Fermi surface, and band structure of lowest-stage nitric-acid—graphite intercalation compounds

Abstract

Results on quantum magnetothermal oscillations in graphite acceptor compounds, ${\mathrm{C}}_{8s}$ (HN${\mathrm{O}}_{3}$) $s=2,3,4$ are presented, including de Haas-van Alphen frequencies and effective masses. The frequency spectrum is different for every stage. Combination frequencies are present in every case and are attributed to magnetic breakdown. The interpretation is based on and confirms the independent two-dimensional zone model of the graphite acceptor compounds. A combination of the band-structure calculation of Blinowski and Rigaux and the folding of these bands in the Brillouin zone of the intercalate compound is used. This gives good agreement for the Fermi surfaces and the effective masses. Numerical values are given for the band parameters. Extra parameters are introduced in order to explain the results. For the second stage a charge-transfer ratio of $f=0.6$ and a Fermi-level shift of 1.08 eV are found. For the third stage 99% of the excess charge is localized in the carbon layer adjacent to the intercalate. The electrostatic energy difference between this layer and the inner one is found to be $2\ensuremath{\epsilon}=1.4$ eV.