| Research Abstract |
On the basis of the experimental data of electronic band structure, phonon dispersion and atomic structure together with the theoretical calculations, we have clarified metallic characters of a monolayr epitaxial film of hexagonal boron nitride on Ni (lll). The interfacial bonding is week on the imcommensurate h-BN layr on Pd and Pt (lll), while the relative strong bonding occurs for the commensurate h-BN layr on Ni (lll). As related to these atomic structures, anomalous features of phonon dispersion have been detected for the commensurate layr : One is the degeneracy of LO and SH modes at the GAMMA point of two dimensional Brillouin zone. Another one is the energy gap at the cross point of the LA and TO branches (Phys.Rev.Lett.79,1997,4609).
In order to understand the those properties, we have calculated the electronic band structure of a monolayr h-BN films by means of LCAO-DV-Xalpha method. The band structures and the local density of states as a function of the interfacial spacing have shown that the hybridization occurs between Pz orbital of B and N and d orbital of Ni. As a result, the metallic character is generated at the interfacial hybridized bands, which results in the observed degeneracy of two phonons.
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