Absence of silicene structure in Si/Ag(110) nanoribbons

A number of studies have proposed that silicene--a single layer of a buckled honeycomb structure of Si atoms--is responsible for the one-dimensional nanoribbon (NR) structures observed to form when silicon is evaporated on Ag(110) [1]. Recent works using Raman and surface differential reflectance spectroscopy have cast doubts upon this interpretation, however [2,3]. Here we propose new reconstruction models for Ag(110)/Si nanoribbon structures based on new Si coverage measurements and evaluate them using density functional theory simulations[4]. Our models are shown to be thermodynamically stable, are consistent with the experimental Si and Ag coverages [5], and yield simulated STM images in excellent agreement with the measured data; in contrast, silicene-based models yield unsatisfactory results. This work provides clear evidence for strongly bound Si-Ag reconstructions on Ag(110), and finds little support for silicene-like structures [1]. [1] A. Kara et al, Journal of Superconductivity and Novel Magnetism 22, 259 (2009); P. De Padova, et al, Applied Physics Letters 96, 261905 (2010); B. Aufray et al, Applied Physics Letters 96, 183102 (2010); C. Lian and J. Ni, Physica B: Condensed Matter 407, 4695 (2012). [2] E. Speiser et al, Applied Physics Letters 104, 161612 (2014). [3] Y. Borensztein, et al, Physical Review B 89, 245410 (2014). [4] C. Hogan et al, in preparation. [5] R. Bernard et al, Physical Review B 88, 121411 (2013)