Formation of a large gap quantum spin Hall phase in a 2D trigonal lattice with three p-orbitals. Issue 12 (7th March 2018)

• Record Type: Journal Article
• Authors: Li, Chong; Jin, Kyung-Hwan; Zhang, Shuai; Wang, Fei; Jia, Yu; Liu, Feng
• Is Part Of: Nanoscale. Volume 10:Issue 12(2018)
• Page Start: 5496
• Page End: 5502
• Publication Date: 2018-03-07
• Subjects: Nanoscience -- Periodicals; Nanotechnology -- Periodicals; 620.505
• DOI: 10.1039/c7nr09067f
• Languages: English
• ISSNs: 2040-3364

Abstract

Abstract : The quantum spin Hall (QSH) phase in a trigonal lattice requires typically a minimal basis of three orbitals with one even parity s and two odd parity p orbitals. Abstract : The quantum spin Hall (QSH) phase in a trigonal lattice requires typically a minimal basis of three orbitals with one even parity s and two odd parity p orbitals. Here, based on first-principles calculations combined with tight-binding model analyses and calculations, we demonstrate that depositing 1/3 monolayer Bi or Te atom layers on an existing experimental Ag/Si(111) surface can produce a QSH phase readily but with three p-orbitals (p x, p y and p z ). The essential mechanism can be understood by the fact while in 3D, the p z orbital has an odd parity, its parity becomes even when it is projected onto a 2D surface so as to act in place of the s orbital in the original minimum basis. Furthermore, non-trivial large gaps, i.e., 275.0 meV for Bi and 162.5 meV for Te systems, arise from a spin–orbit coupling induced quadratic p x –p y band opening at the Γ point. Our findings will significantly expand the search for a substrate supported QSH phase with a large gap, especially in the Si surface, to new orbital combinations and hence new elements.