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Soft phonon, dynamical fluctuations, and a reversible phase transition: indium chains on silicon
C González1, F Flores, J Ortega
1Departamento de Física Teórica de la Materia Condensada, Universidad Autónoma, 28049 Madrid, Spain.
Physical Review Letters
|May 23, 2006
Summary
The In/Si(111)-(4 x 1) surface exhibits a reversible metal-insulator transition. This study reveals the transition originates from dynamical fluctuations between degenerate ground states in indium chains.
Area of Science:
- Surface science
- Condensed matter physics
- Materials science
Background:
- The Indium/Silicon(111)-(4 x 1) surface is a quasi-one-dimensional system.
- It displays a reversible structural and electronic (metal-insulator) phase transition upon cooling.
Purpose of the Study:
- To elucidate the atomic and electronic origins of the controversial phase transition.
- To investigate the ground state and dynamical behavior of the In/Si(111)-(4 x 1) surface.
Main Methods:
- First-principles simulation techniques.
- First-principles molecular dynamics simulations.
Main Results:
- The ground state is identified as insulating (4 x 2) indium chains with specific shear distortions.
- Dynamical fluctuations between degenerate ground states drive the (4 x 1) <--> (8 x 2) phase transition at high temperatures.
- Metallicity is linked to a low energy cost for shear distortion.
Conclusions:
- The controversial phase transition in In/Si(111)-(4 x 1) is explained by atomic and electronic structure.
- Dynamical fluctuations and shear distortion energetics are key to understanding the metal-insulator transition.
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