Fermi gap stabilization of an incommensurate two-dimensional superstructure

The compressed, incommensurate approximately (9.5 x 9.5) moire superstructure of the Ag monolayer on Cu(111) displays a filled surface state band with a Fermi energy gap at the Brillouin zone boundary. By contrast, the surface band is gapless for the less compressed, commensurate (9 x 9) moire of tw...

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Bibliographic Details
Published in:Physical review letters 2005-01, Vol.94 (1), p.016103-016103, Article 016103
Main Authors: Schiller, F, Cordón, J, Vyalikh, D, Rubio, A, Ortega, J E
Format: Article
Language:English
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Summary:The compressed, incommensurate approximately (9.5 x 9.5) moire superstructure of the Ag monolayer on Cu(111) displays a filled surface state band with a Fermi energy gap at the Brillouin zone boundary. By contrast, the surface band is gapless for the less compressed, commensurate (9 x 9) moire of two Ag layers. A simple estimate of the energy gain rendered by opening this gap gives a value similar to the elastic energy change required to modify the commensurate structure, thereby suggesting that the approximately (9.5 x 9.5) incommensurate phase is stabilized by such a gap opening. The possible presence of a charge density wave state is discussed.
ISSN:0031-9007
1079-7114
DOI:10.1103/PhysRevLett.94.016103