?@ One-dimensional (1D) conducting materials in nanometer scale is an essential ingredient of the nano and molecular electronics. Moreover, the fundamental physical properties of 1D metallic electrons are attractive with various exotic ground states and excitations. As an unconventional form of 1D metallic systems in (sub)nanometer scale, we have investigated the physical properties of self-organized metallic atomic chains or nanowires on flat and vicinal Si(111) surfaces. These atomic chains or nanowires were found to have well defined 1D metallic band structures with the notable examples of 4x1-In on Si(111) [1, 2, 3], 5x2-Au on Si(111) [4], 1x2-Au on Si(557) [5], and 1x2-Au on Si(553) [6], and Pb on Si(557) [7]. The Peierls-type phase transitions into 2kF of 3kF charge-density-wave ground states were observed in these systems due to the 1D band structure [1-3, 5, 6]. In the present talk, I will first review the phase transitions observed and the major on-going debates on them. Then, a few new issues on these systems will be discussed such as (i) the defect control over the transition temperature and the band gap [4], (ii) atomic scale characterization of the intrinsic 1D fluctuations [8], (iii) the confined soliton, and (iv) the mechanism of stabilization of the metallic wires at a very low temperature [7]. Future direction of this research field will be introduced.
References
1. H. W. Yeom et al., Phys. Rev. Lett. 82, 4898 (1999).
2. J. R. Ahn et al., Phys. Rev. Lett. 93, 106401 (2004).
3. S. J. Park, Phys. Rev. Lett. 93, 106402 (2004).
4. W. H. Choi et al., submitted.
5. J. R. Ahn et al., Phys. Rev. Lett. 91, 196403 (2003).
6. J. R. Ahn et al., Phys. Rev. Lett. 95, 196402 (2005).
7. K. S. Kim et al., submitted.
8. S. J. Park et al., Phys. Rev. Lett. 95, 126102 (2005).
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