Disproportionation phenomena on free and strained Sn/Ge(111) and Sn/Si(111) surfaces |
| |
Authors: | Ballabio G Profeta G de Gironcoli S Scandolo S Santoro G E Tosatti E |
| |
Institution: | International School for Advanced Studies (SISSA) and Istituto Nazionale di Fisica della Materia (INFM/DEMOCRITOS), via Beirut 2-4, I-34014, Trieste, Italy. |
| |
Abstract: | Distortions of the sqrt3]x sqrt3] 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 x 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 distortions. Negative strain attracts pseudocharge from the valence band causing first a (3 x 3)-2U distortion (Q=4) on both Sn/Ge and Sn/Si, and eventually a (sqrt3] x sqrt3])-3U ("all up") state with Q=6. The possibility of a fluctuating phase in unstrained Sn/Si(111) is discussed. |
| |
Keywords: | |
本文献已被 PubMed 等数据库收录! |
|