Disproportionation Phenomena on Free and Strained Sn/Ge(111) and Sn/Si(111) Surfaces

Abstract

Distortions of the $\sqrt{3}\times \sqrt{3}$ Sn/Ge(111) and Sn/Si(111) surfaces are shown to reflect a disproportionation of an integer pseudocharge, $Q$, related to the surface band occupancy. A novel understanding of the $(3\times 3)$-1U (``1 up, 2 down'') and 2U (``2 up, 1 down'') distortions of Sn/Ge(111) is obtained by a theoretical study of the phase diagram under strain. Positive strain keeps the unstrained value Q=3 but removes distorsions. Negative strain attracts pseudocharge from the valence band causing first a $(3\times 3)$-2U distortion (Q=4) on both Sn/Ge and Sn/Si, and eventually a $(\sqrt{3}\times \sqrt{3})$-3U (``all up'') state with Q=6. The possibility of a fluctuating phase in unstrained Sn/Si(111) is discussed.

arXiv commentRevtex, 5 pages, 3 figures

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Cited by in corpus (4)

• Triangular Mott-Hubbard Insulator Phases of Sn/Si(111) and Sn/Ge(111) Surfaces
• Realistic modeling of the electronic structure and the effect of correlations for Sn/Si(111) and Sn/Ge(111) surfaces
• Surface Phase Transitions Induced by Electron Mediated Adatom-Adatom Interaction
• The electronic structure of a doped Mott-Hubbard surface