Strongly interacting electrons in synthetic superlattices

Introduction

Recent experiments on a class of atomically-thin two-dimensional materials, called moiré superlattice systems, have uncovered an entirely new and fascinating world of enigmatic strong-correlation physics and superconductivity. This project will develop theoretical models to explain these intriguing experimental observations.

Role of Numerical Simulations

Numerical simulations will play an important role in guiding the theoretical models. An overarching goal is also to explore what lessons we can learn from moiré materials that advance our understanding of other paradigmatic strongly-correlated electron materials such as the copper-oxide superconductors.

Project Objectives

The particular objectives of this project are to understand:

1. The nature of the broken-symmetry orders which appear in different moiré materials.
2. The origin of superconductivity observed in carbon-based moiré materials, and the role of the repulsive Coulomb interaction in the electron pairing mechanism.
3. Whether exotic fractionalized metals are realized in moiré materials, and their potential role in explaining the ‘pseudo-gap’ regime.
4. The Mott insulating ground states of twisted transition-metal dichalcogenides, and the parameter regimes where these correspond to long-range-entangled spin liquids.

Importance of the Objectives

These objectives address some of the most important and long-standing problems in condensed matter physics, such as:

• Developing a theoretical understanding of electron pairing in the presence of strong repulsive interactions.
• Understanding the nature of the pseudo-gap phase, which seems to be ubiquitous in strongly-correlated materials.

Expected Outcomes

The results obtained in this project will guide future experiments and enhance the possibility of realizing exotic phases of quantum matter, such as spin liquids, in the lab. The experimental observation of spin liquids in moiré systems would constitute a milestone in the field of strongly-correlated materials.