Inducing quantum phase transitions in nontopological insulators via atomic control of substructural elements

Topological insulators are an important family of quantum materials that exhibit a Dirac point (DP) in the surface band structure but have a finite band gap in bulk. A large degree of spin-orbit interaction and low band gap is a prerequisite for stabilizing DPs on selective atomically flat cleavage planes. Tuning of the DP in these materials has been suggested via modifications to the atomic structure of the entire system. Using the example of ${\mathrm{As}}_{2}{\mathrm{Te}}_{3}$ and ${\mathrm{ZnTe}}_{5}$, which are not TIs, we show that a quantum phase transition can be induced in atomically flat and stepped surfaces, for ${\mathrm{As}}_{2}{\mathrm{Te}}_{3}$ and ${\mathrm{ZrTe}}_{5}$, respectively. This is achieved by establishing a framework for controlling electronic properties that is focused on local perturbations at key locations that we call substructural elements. We exemplify this framework through a unique method of isovalent sublayer anion doping and biaxial strain.