Surface phase transition in H/W(110) induced by tuning the fermi surface nesting vector by hydrogen loading

Area of Science:

• Surface science
• Condensed matter physics
• Materials science

Background:

• W(110) surfaces with one monolayer of hydrogen exhibit Fermi nesting in electronic surface states.
• The nesting vector (qN) is typically 0.9 Å⁻¹ along [001].

Purpose of the Study:

• To investigate the controlled tuning of the Fermi nesting vector (qN) in W(110) by additional hydrogen adsorption.
• To understand the relationship between qN, surface charge density wave (CDW) formation, and surface symmetry changes.

Main Methods:

• Inelastic He-atom scattering to probe electronic surface states and Fermi nesting.
• Controlled hydrogen adsorption on W(110) surfaces.

Main Results:

• Additional hydrogen adsorption allows for controlled tuning of the Fermi nesting vector (qN).
• As qN approaches the commensurate value of 1.0 Å⁻¹, its signature in scattering experiments becomes more pronounced.
• A surface charge density wave (CDW) develops, causing the surface symmetry to change from c(2x2) to p(8x2) as qN disappears.
• The tuning of qN is linked to energetic shifts in spin-polarized electronic surface states.

Conclusions:

• Hydrogen adsorption provides a method to tune Fermi nesting in W(110).
• The transition to a surface charge density wave (CDW) is associated with the complete nesting of electronic surface states.
• Energetic shifts in spin-polarized surface states are crucial for the formation of the CDW and the observed surface reconstruction.