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We perform {\it ab initio} electronic structure calculations for the metal-carbon nanotube (CNT) interfaces with encapsulated fullerenes (C$_{82}$) or metallofullerenes (La@C$_{82}$). Gold and aluminum layers are chosen as typical examples of metals with a large work function and a small work function, respectively. It is found that the encapsulation of the fullerene species can affect the Schottky barrier height at the metal-CNT interface. We show that the fullerene-derived localized state could weakly pin the metal Fermi level in the gap of the nanotube. We suggest that the transport properties of the metallofullerene-encapsulated CNT should be explained in terms of the Schottky barrier adjustment rather than the band gap reduction model whose validity has been debated in recent publications.


We perform {\it ab initio} electronic structure calculations for the metal-carbon nanotube (CNT) interfaces with encapsulated fullerenes (C$_{82}$) or metallofullerenes (La@C$_{82}$). Gold and aluminum layers are chosen as typical examples of metals with a large work function and a small work function, respectively. It is found that the encapsulation of the fullerene species can affect the Schottky barrier height at the metal-CNT interface. We show that the fullerene-derived localized state could weakly pin the metal Fermi level in the gap of the nanotube. We suggest that the transport properties of the metallofullerene-encapsulated CNT should be explained in terms of the Schottky barrier adjustment rather than the band gap reduction model whose validity has been debated in recent publications.