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Strong Quantum Size Effects in Pb(111) Thin Films Mediated by Anomalous Friedel Oscillations...

Publication Type
Journal
Journal Name
Physical Review Letters
Publication Date
Page Number
066101
Volume
105
Issue
6

Using first-principles calculations within density functional theory, we study Friedel oscillations (FOs)
in the electron density at different metal surfaces and their influence on the lattice relaxation and stability
of ultrathin metal films.We show that the FOs at the Pb(111) surface decay as 1=x with the distance x from
the surface, different from the conventional 1=x2 power law at other metal surfaces. The underlying
physical reason for this striking difference is tied to the strong nesting of the two different Fermi sheets
along the Pb(111) direction. The interference of the strong FOs emanating from the two surfaces of a
Pb(111) film, in turn, not only results in superoscillatory interlayer relaxations around the center of the
film, but also determines its stability in the quantum regime. As a simple and generic picture, the present
findings also explain why quantum size effects are exceptionally robust in Pb(111) films.