Self-Encapsulation of Silicene in Cubic Diamond Si: Topological Semimetal in Covalent Bonding Networks

Abstract

Silicene has a two-dimensional buckled honeycomb lattice and is chemically reactive because of its mixed sp 2 −sp 3 bonding character unlike graphene. Despite recent advances in epitaxial growth, it remains a great challenge to synthesize a stable silicene layer. Here, we propose an encapsulation method, in which silicene is self-encapsulated between Si(110) layers in the cubic diamond lattice and effectively protected from reaction with environmental gases. Although Si atoms are all fourfold coordinated, selfencapsulated silicene exhibits the band topology of Dirac semimetals. In a superlattice structure, in which silicene is periodically encapsulated between Si(110) layers, we also find a topological transition from a normal semiconductor to a topological nodal line semimetal as the number of Si(110) layers increases. Our results provide insights into the design of a stable silicene layer that retains the nontrivial band topology and is useful for applications of Si-based devices.

Design of Single-Layer Metasurface Filter by Conformational Space Annealing Algorithm for 5G mm-Wave Communications

“…We designed the frequency response characteristics needed for 5G applications using a very general design scheme based on the conformational space annealing (CSA) algorithm [37], [38]. CSA, a global optimization method used in the present work, has been applied to many optimization problems [39]- [47]. Unlike genetic algorithm or particle swarm optimization, there is a special feature that directly controls the differences between the candidate solutions.…”