Functionalized germanene as a prototype of large-gap two-dimensional topological insulators

We propose two-dimensional (2D) topological insulators (TIs) in functionalized germanenes (GeX, X$\phantom{\rule{0.16em}{0ex}}=\phantom{\rule{0.16em}{0ex}}$H, F, Cl, Br, or I) using first-principles calculations. We find GeI is a 2D TI with a bulk gap of about 0.3 eV, while GeH, GeF, GeCl, and GeBr ... View More