EVIDENCE FOR A DRIVING MECHANISM OF THE W(001) RECONSTRUCTION

We report the first experimental observation of a gap-opening and changes of the Fermi surface contours upon reconstruction of the W(001) surface. A gap Delta greater than or equal to 0.6 eV is found to form at (X) over bar', a new surface Brillouin zone boundary along the azimuth of the reconstructed (root 2 x root 2)R45 degrees structure. The large gap and the Fermi surface contours of which the curvatures remain essentially unaltered through reconstruction suggest that the reconstruction is driven primarily by a strong-coupling charge density wave mechanism. (C) 1997 Elsevier Science B.V.X1110sciescopu