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Nano-structuration of surfaces is a powerful way to drive electronic properties at nanometric scale and test basic solid state physics concepts. Ideal one-dimensional systems can be elaborated by using the anisotropic properties of vicinal surfaces. Indeed, the confinement of surface electrons by steps has been already obtained on Au vicinal surfaces leading to quantum well surface states [1].
We evidence here that parallel to the steps, the one-dimensional surface electron gas feels the weak super-periodic potential induced by the Au surface reconstruction. Therefore, a careful analysis of high resolution angle-resolved photoemission spectroscopy (ARPES) data evidences the opening of several gaps in the surface band structure of Au(232321) and Au(788) surfaces. More, scanning tunneling spectroscopy (STS) allowed us to probe the corresponding energy dependence of the surface electronic density through the gaps. From a methodological point of view, the values of the gaps and the phase of the electronic density allow to estimate the amplitude and the shape of the reconstruction potential which yields the electronic Bragg diffraction [2]. A quantitative analysis is derived in the framework of a simple pseudo-potential approach in agreement with our experimental data. The redistribution of ARPES spectral weight over the different Brillouin zones is also discussed [3]. In addition, the superpotential has been modified by forming long-range ordered patterns of Ag and Co nano-islands [3-4]. On one hand, Co islands appear as strongly repulsive barrier leading to an enhancement of the surface potential putting it in the strong coupling limit. On the other hand, new quantized surface states appear inside Ag islands whose energies can be tailored by the deposition rate and the miller index of the vicinal surface [4]. A long range homogeneity of the surface state properties is achieved over a macroscopic scale.
[1] Mugarza et al., Phys. Rev. Lett. 87, 107601 (2001) [2] Didiot et al., Phys. Rev. B 74, R081404 (2006). [3] C. Didiot et al., proceedings of ECOSS24, September 4-8th, Paris (2006), to appear in Surface Science C. Didiot et al., Surf. Sci. 600, 3917 (2006) [4] C. Didiot et al., proceedings of ICSFS-13, November 6-10, Bariloche (2006), to appear in Applied Surface Science. |
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