We propose that the indirect adatom-adatom interaction mediated by the conduction electrons of a metallic surface is responsible for the 3×3⇔3×3 structural phase transitions observed in Sn/Ge (111) and Pb/Ge (111). When the indirect interaction overwhelms the local stress field imposed by the substrate registry, the system suffers a phonon instability, resulting in a structural phase transition in the adlayer. Our theory is capable of explaining all the salient features of the 3×3⇔3×3 transitions observed in Sn/Ge (111) and Pb/Ge (111), and is in principle applicable to a wide class of systems whose surfaces are metallic before the transition.
@article{arxiv.cond-mat/0303434,
title = {Surface Phase Transitions Induced by Electron Mediated Adatom-Adatom Interaction},
author = {Junren Shi and Biao Wu and X. C. Xie and E. W. Plummer and Zhenyu Zhang},
journal= {arXiv preprint arXiv:cond-mat/0303434},
year = {2007}
}