Realizing designer quantum matter in van der Waals heterostructures

Introduction

Conventional materials hosting exotic quantum phases typically have complex atomic structures, inhomogeneities from defects, impurities, and dopants, making it difficult to rationally engineer their electronic properties. This can be overcome using van der Waals (vdW) heterostructures that allow an almost arbitrary selection of the heterostructure building blocks, including:

• Metals and insulators
• Charge-density wave systems
• Superconductors
• Magnets
• Correlated insulators
• Ferroelectrics

vdW Heterostructures

In a vdW heterostructure, the layers interact only through vdW forces and can keep their intrinsic properties. However, proximity effects cause properties to “leak” between the adjacent layers and allow for the creation of exotic quantum mechanical phases that arise from the interactions between the layers.

These key features have recently made it possible to realize exotic quantum phases by design and engineer responses that do not occur in natural materials.

Fabrication and Targeted Structures

I will now exploit these features and fabricate heterostructures using molecular-beam epitaxy (MBE) to target:

1. Artificial heavy fermion heterostructures realizing unconventional superconductivity
2. Artificial 2D multiferroic materials
3. 2D quantum spin liquids

The atomic scale geometry and electronic properties of the resulting heterostructures will be characterized using low-temperature scanning tunneling microscopy (STM) and spectroscopy (STS).

Future Opportunities

These designer heterostructures will have engineered electronic phenomena with atomically precise structures and controlled interactions. This will lead to exciting new opportunities in fundamental condensed matter physics and subsequently, in quantum devices realizing completely new functionalities.

They answer the pressing need for novel quantum materials with tunable properties to enable completely new types of approaches in quantum technologies. This will keep Europe at the forefront of the second quantum revolution and create yet unimagined future breakthrough technologies.