Engineering ideal helical topological networks in stanene via Zn decoration

Abstract

The xene family of topological insulators plays a key role in many proposals for topological electronic, spintronic, and valleytronic devices. These proposals rely on applying local perturbations, including electric fields and proximity magnetism, to induce topological phase transitions in xenes. However, these techniques lack control over the geometry of interfaces between topological regions, a critical aspect of engineering topological devices. We propose adatom decoration as a method for engineering atomically precise topological edge modes in xenes. Our first-principles calculations show that decorating stanene with Zn adatoms exclusively on one of two sublattices induces a topological phase transition from the quantum spin Hall (QSH) to quantum valley Hall (QVH) phase and confirm the existence of spin-valley polarized edge modes propagating at QSH/QVH interfaces. We conclude by discussing technological applications of these edge modes that are enabled by the atomic precision afforded by recent advances in adatom manipulation technology. The authors propose sublattice-selective decoration by Zn adatoms as a method to engineer precise topological edge modes in xenes. First-principles calculations on Zn decorated stanene reveal a quantum spin Hall (QSH) to quantum valley Hall (QVH) transition and spin-valley polarized modes propagating at the QSH/QVH interface.