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O: Fachverband Oberflächenphysik

O 7: Metal Substrates: Adsorption I

O 7.3: Vortrag

Montag, 26. März 2007, 11:45–12:00, H39

Surface phase transition in H/W(110) achieved by tuning the Fermi surface nesting vector by Hydrogen loading — Yoichi Yamada, •Wolfgang Theis, and Karl-Heinz Rieder — Freie Universität Berlin, Berlin, Germany

At a hydrogen coverage of one monolayer, W(110) is known to exhibit a Fermi nesting in its electronic surface states with an incommensurate nesting vector of 0.9 Å⁻¹ and a resulting phonon anomaly. Here we show that additional H-adsorption allows a controlled tuning of the nesting vector. As the nesting vector approaches the commensurate value of 1.0 Å⁻¹ the phonon anomaly becomes more pronounced, finally disappearing as the surface reconstructs from a clean surface c(2x2) to a p(8x2) superstructure. The gradual change in the nesting vector is attributed to an energetic shift of the surface state as the surface is loaded with additional hydrogen.