Engineering artificial topological phases via superlattices

TL;DR

This paper experimentally maps the phase diagrams of topological superlattices made from Bi2Se3 and In2Se3, revealing how their electronic properties evolve with layer thickness and enabling the engineering of artificial topological phases.

Contribution

It provides the first experimentally-verifiable phase diagrams of topological superlattices combining topological and normal insulators, bridging theory and experiment.

Findings

Electronic properties depend on layer thicknesses.

Weak antilocalization reveals conducting channel evolution.

Potential to create artificial topological phases.

Abstract

The search for new topological materials and states of matter is presently at the forefront of quantum materials research. One powerful approach to novel topological phases beyond the thermodynamic space is to combine different topological/functional materials into a single materials platform in the form of superlattices. However, despite some previous efforts, there has been a significant gap between theories and experiments in this direction. Here, we provide the first detailed set of experimentally-verifiable phase diagrams of topological superlattices composed of archetypal topological insulator (TI), Bi$_{2}$Se$_{3}$, and normal insulator (NI), In$_{2}$Se$_{3}$, by combining molecular-level materials control, low-temperature magnetotransport measurements, and field theoretical calculations. We show how the electronic properties of topological superlattices evolve with unit-layer thicknesses and utilize the weak antilocalization effect as a tool to gain quantitative insights into the evolution of conducting channels within each set of heterostructures. This orchestrated study opens the door to the possibility of creating a variety of artificial-topological-phases by combining topological materials with various other functional building blocks such as superconductors and magnetic materials.