The secret to all of these fascinating phenomena lies in the unique nature of the electronic properties of graphite, where the low energy excitations resemble massless Dirac fermions. Also, the recent discovery that the electronic properties of thin graphite samples can be modified by externally applied voltage, in such a way that these systems can be switched from n-type to p-type carriers NovoselovSci ZhangPRL, has raised a great potential for carbon-based nanoelectronics. Although graphite is one of the most widely studied materials, it continues to provide scientists with new and interesting challenges as recently testified by a wide range of novel discoveries in the field, such as novel quantum Hall effect Kopelevich, room temperature ferromagnetism KopelevichPRB, metal-insulator-like transition Kopelevich, and superconductivity GIC. One of the prime examples for the unique properties of carbon is graphite. These results provide new insights on the unusual nature of the electronic and transport properties of graphite. Moreover, the lattice disorder strongly affects the low energy excitations, giving rise to new localized states near the Fermi level. We also report the first ARPES signatures of electron-phonon interaction in graphite: a kink in the dispersion and a sudden increase in the scattering rate. At low binding energy, we observed signatures of massless Dirac fermions with linear dispersion (as in the case of graphene), coexisting with quasiparticles characterized by parabolic dispersion and finite effective mass. As a consequence of the interlayer coupling, we observed for the first time the splitting of the π bands by ≈0.7 eV near the Brillouin zone corner K. We found that the nature of the low energy excitations in graphite is particularly sensitive to interlayer coupling as well as lattice disorder.
In this paper, we present a high resolution angle resolved photoemission spectroscopy (ARPES) study of the electronic properties of graphite.
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