Optical and electronic characterization of Au nanowires on vicinal Si(111) surfaces

An efficient route for fabricating regular and spatially-dense nanostructure arrays over a large area is to exploit self-organization of adsorbates on a substrate featuring a periodic pattern at the nanoscale [1]. One such possibility is the engineering of one-dimensional (1D) quantum structures on stepped surfaces. For instance, the adsorption of gold acts to stabilize flat and stepped (vicinal) Si(111) surfaces leading to reconstructions having 1D features that are also interesting from a fundamental perspective. For instance, the prototypical Si(111)-(5x2)-Au surface has been reported to exhibit a spontaneous period doubling accompanied by an unusual "double" Peierls mechanism [2], while intrinsic magnetic chains have been predicted at step edges of Si(553)-Au and Si(557)-Au [3]. The exact structural, electronic and magnetic properties of these monatomic wires depends on several factors, including the step width [1] and step morphology [4], the presence of adatoms [2,3], and spin-orbit coupling [2,5]. The need for precise atomistic simulations is clear from the ongoing controversy over the basic microscopic structure of several such systems [2,6]. In this talk I will present a joint experimental-theoretical study that utilizes reflectance anisotropy spectroscopy (RAS) as a characterization tool [5,7], and demonstrate its power in resolving some of these controversies [8]. [1] F. Himpsel et al, J. Phys.: Cond. Mat 13, 11097 (2001) [2] S.C. Erwin et al, Phys. Rev. B 80, 155409 (2009) [3] S.C. Erwin and F. J. Himpsel, Nature Commun. 1:58 (2010). [4] N. McAlinden and J. F. McGilp, Euro. Phys. Letters 92, 67008 (2010) [5] C. Hogan, N. McAlinden, J. McGilp, Phys Stat Sol B 249, 1095-1104 (2012) [6] T. Abukawa and Y. Nishigaya, Phys. Rev. Lett. 110, 036102 (2013). [7] N. McAlinden and J. F. McGilp, J. Phys. Condens. Matter 21, 474208 (2009) [8] C. Hogan, E. Ferraro, N. McAlinden, J. F. McGilp, Phys. Rev. Lett. 111, 087401 (2013).