Phase Transformation and Proximity Coupling in Lateral Heterostructures of Metal Dichalcogenides

Two-dimensional (2D) materials are atomically thin with atoms strongly bonded within layers but weakly between layers. This weak interlayer coupling allows for the vertical stacking of different materials to form heterostructures with interesting properties and applications. In contrast, a lateral heterostructure consists of different 2D materials placed side by side with one-dimensional boundaries with strong bonding.

The difference is akin to a stack of different plates (vertical) vs. being spread out on a table (lateral). This project will investigate novel phenomena that arise in lateral heterostructures with exposed boundaries on the surface. This allows for spatially resolved exploration of new interfacial physics and the rational design of heterostructures with desired properties.

For example, the PIs have previously demonstrated that they can convert a 2D material from a semiconductor to a topological insulator. The latter is a state of quantum matter that behaves as an insulator in its interior but as a conductor on its surface. Coupling a topological insulator with a superconductor may give rise to topological superconductivity, which can be used for quantum computers.

This project also aims to providing training ground for a competitive workforce in materials research. The PIs will strive to enhance the diversity of this workforce by actively recruiting and mentoring female and minority students. Research-based educational materials are to be integrated with outreach activities to engage the public.

The rapid advances in two-dimensional (2D) materials enable the integration of atomically thin layers with vastly different properties into heterostructures, where exotic behaviors that are not accessible in individual layers may emerge. Most studies of 2D heterostructures have been pursued on vertical geometries to take advantages of van der Waals interaction for creating a passivated interface with low density of interfacial electronic states.

In contrast, lateral heterostructures uniquely allow for the heterointerfaces, which are typically buried in the bulk, to be directly exposed on surface for unravelling boundary-induced behaviors by scanning probe techniques. The PI aims to explore the versatility of phase transformation scheme empowered by the core-shell lateral architecture and apply the proximity studies to transition metal dichalcogenides (TMDCs) with correlated electronic behaviors.

The local perturbations associated with the lateral boundary could provide the knob to tune the interactions and thus facilitate the understanding of collective electronic states as well as their interplay in the monolayer regime. This research also aims to address the feasibility of applying lateral heterostructures to induce topological superconductivity on the edge of 2D topological insulators.

It sheds light on the investigation of Majorana physics using lateral templates of 2D materials, holding potential to implement topological qubits in fault-tolerant quantum computation.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.