Comparative Study on Electronic Structure of Doped Fullerenes and High-Tc Oxide Superconductors

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Photoemission spectroscopy shows that a very narrow quasi-particle-peak (coherent spectra) and a broad distribution of density-of-states (incoherent spectra) coexist near the Fermi level (E_F) in K_3C_<60>, while the narrow quasi-particle-peak at E_F is not present in nonmetallic K_4C_<60>. This shows that K_4C_<60> is a semiconductor with an energy gap at E_F contrary to the prediction from band structure calculations, and suggests that electron correlation is important in understanding the electronic structure of doped fullerenes, both metallic K_3C_<60> and nonmetallic K_4C_<60>. The combination of photoemission, inverse photoemission and polarized oxygen-K-absorption in high-Tc oxide superconductors shows that the hole-doping results in a similar electronic structure to that of doped fullenes with the coexistence of a very narrow peak and a broad distribution of density-of-states near E_F. These results are consistent with the highly-correlated Fermi-liquid picture. We discuss the similarities and differences between doped fullerenes and high-Tc oxides superconductors based upon the comparison of their electronic structures.High-Tc superconductorsdoped fullerenesFermi-liquidelectron correlation
東北大学の論文
1994-03-25