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|Title:||Fermi surface of donor and acceptor graphite intercalation compounds|
|Abstract:||<p>The Fermi surfaces and the electronic properties of the donor-type stage-1 C₈K and stage-2 C₂₄K, as well as the acceptor-type stage-2 BiCl₃, stage-3 HgCl₂ and stage-3 SbF₅ graphite intercalation compounds were investigated by means of the de Haas-van Alphen effect. The dHvA spectra of the stage-1 C₈K exhibit two dHvA frequencies, 3126 T and 4250 T. The corresponding effective masses were 0.86 m₀ and 0.92 m₀, respectively. The angular dependence of the dHvA frequencies for a direction within ±18° of the c-axis showed that there are both three-dimensional and two dimensional parts of the Fermi surfaces in C₈K. The three-dimensional Fermi surface has a cross-sectional area corresponding to the dHvA frequency of 3126 T. The charge transfer per potassium atom measured from the dHvA effect is 0.97. This implies that the potassium is ionized completely. These dHvA experimental results support both the Tatar and Rabii model and the revised Ohno, Nakao and Kamimura model for C₈K. Two dominant dHvA frequencies were obtained in stage-2 C₂₄K. They are 286 T and 2570 T, respectively. The predictions of Blinowski's model are in agreement with the experimental data. The charge transfer per potassium is found to be 0.88. This suggests that the potassium s-band is above the Fermi level in C₂₄K. The dHvA measurements for the acceptor compounds show that the stage-2 BiCl₃ GIC had two dHvA frequencies, 327T and 1012T, and each stage-3 compound had three dominant frequencies. They are 121T, 523T and 664T for HgCl₂, and 172T, 656T and 852T for SbF₅. The cyclotron masses corresponding to the dHvA frequencies for these compounds were measured from the temperature dependence of the dHvA amplitudes. The theoretical predictions of the dHvA frequencies and the cyclotron masses from the Blinowski's band models for stage-2 and stage-3 compounds are in agreement with the experimental results. The angular dependence of the dHvA frequencies show that the Fermi surfaces in these acceptor compounds are cylinders. This proves the two-dimensionality of the band structures of the Blinowski model. In addition, the charge transfer coefficient per carbon atom is directly determined from the observed sum of the dHvA frequencies for each of the acceptor compounds. The fractional charge distribution along the c axis of the stage-3 compounds is found to be between the uniform charge distribution model and the metallic sandwich model.</p>|
|Appears in Collections:||Open Access Dissertations and Theses|
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