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Two-dimensional elemental topological insulators including silicene, germanene and stanene are currently the hottest topics in condensed matter physics. We first review the recent progress on electronic and topological properties of their monolayers from a fundamental viewpoint. Next, we describe their experimental realizations by epitaxial growth and their actual physical properties. We start with the description of the topological nature of generic Dirac systems and then apply it to silicene by introducing the spin and valley degrees of freedom. Based on them, we classify all topological insulators in the general honeycomb system. We discuss topological electronics based on honeycomb systems. We introduce the topological Kirchhoff law, which is a conservation law of topological edge states. A field effect topological transistor is proposed based on the topological edge states. We show that the conductance is quantized even in the presence of random distributed impurities. Monolayer topological insulators will be a key for future topological electronics and spin-valleytronics. The outstanding example of the realization of such monolayer Si, Ge and Sn novel artificial allotropes is the canonical 3× 3 reconstructed epitaxial silicene phase grown in situ under ultra-high vacuum on the silver (111) surface. Its realization in 2012 has preceded the synthesis of germanene, followed by that of stanene, respectively on Au (111) and Bi2Te3 substrates. Further growth of Si and Ge over monolayer epitaxial silicene and germanene leads to layered thin films displaying Dirac fermion characteristics. Amazingly, Si deposition
Società Italiana di Fisica
Publication date: 
16 Feb 2018

M. Ezawa, E. Salomon, P. De Padova, D. Solonenko, P. Vogt, M. E. Dávila, A. Molle, T. Angot, G. Le Lay

Biblio References: 
Volume: 41 Issue: 3 Pages: 175-224
La Rivista del Nuovo Cimento