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Séminaire - Guy Lelay

Mardi 17 Janvier 2023 à 11h00, Guy Lelay (Aix-Marseille Université) donnera un séminaire intitulé "OD, 1D and 2D Quantum Topological Group IV Artificial Materials Created by Design".


Silicene, realized in 2012, the silicon-based artificial monoelemental counterpart of graphene, is the first synthetic two-dimensional (2D) Dirac material. Its legacy, called Xenes, are new 2D allotropes of a number of elements from B to Te. From column IV elements, silicene, germanene, stanene, and plumbene have sizeable spin-orbit couplings, allowing for the quantum spin Hall effect, possibly even above room temperature.
Quantum spin Hall insulators generate enormous interest with the prospects of breakthrough applications from Field-Effect Transistors to spintronics and quantum computation.
In this seminar I will compare emergent properties and outstanding multifaceted outcomes of
- i- tailored single phase silicene, germanene, stanene and plumbene sheets formed in situ under ultra-high vacuum on Al(111), Ag(111), Au(111) or Pd(111) respectively, offering, e.g., strinking prospects for topological thermoelectrics,
- ii- Germanene, seemingly two years younger than silicene and its first successor, which had
in reality, its signature encrypted already 51 years ago in a strange low energy electron
diffraction pattern. Having no Rosetta stone to decipher it, this pattern could not be decoded and remained buried in a 1971 thesis. It was excavated recently and duly interpreted in terms of germanene synthesis through a bottom-up approach,
- iii- 0D penta-silicene nanodots, strickly comprising 12 Si atoms, as well as massively parallel 1D silicon nanoribbons grown on Ag(110), with possible applications as 1D helical channels in future devices, and for the emergence and control of Majorana fermions.

Guy Le Lay, Professor Emeritus at Aix-Marseille University, is the 2021 Laureate of the Fernand Holweck Medal and Prize awarded by the Institute of Physics and the Société Française de Physique ‘For pioneering the realization and study of the emerging properties of new twodimensional allotropes of silicon, germanium, tin and lead, and coined artificial Xenes’.


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