UNICOSMOS · Unravelling the intertwined correlated states of matter in moiré superlattices

Unravelling the intertwined correlated states of matter in moiré superlattices

The UNICOSMOS project is focused on understanding the quantum properties of materials known as moiré superlattices or moiré materials from an atomistic point of view. Moiré superlattices are formed when two-dimensional (2D) materials such as graphene or transition-metal dichalcogenides (TMDs) are stacked on top of each other with a slight twist or mismatch in their lattice structures. This results in a nano-scale, periodic pattern called a moiré pattern. In these moiré superlattices, the mismatch in alignment alters the electronic, optical, and mechanical properties of the original 2D materials. Since 2018, experimentalists have successfully created moiré superlattices, leading to discoveries such as twisted bilayer graphene's unconventional superconductivity and other correlated phases. This has generated tremendous excitement and given rise to the new field of twistronics. These correlated phenomena are linked to the formation of "electronic flat bands," where electron movement is restricted, leading to an enhancement of electron-electron correlation and novel quantum states. However, theoretical understanding of the interplay between these quantum states remains limited, especially due to the computational challenges involved in modeling the intricate quantum interactions within such materials containing thousands of atoms. The project's objective is to develop computational methods to better understand these emerging quantum phases and explore their potential applications in quantum technologies like quantum computing and optoelectronics. The research leverages a combination of computational approaches, including tight-binding models and classical force field methods, to simulate these complex materials in ways that current state-of-the-art methods struggle to achieve. The UNICOSMOS project is organized around three primary research objectives (ROs) to explore and understand the complex quantum phases in moiré superlattices: 1. RO1: Develop tight-binding for moiré systems of transition metal dichalcogenides (TMDs) to study the formation of flat bands and their evolution with twist angle and chemical composition. 2. RO2: Use this framework to extract parameters for relevant model Hamiltonians of moiré flat bands. 3. RO3: Apply advanced methods to solve correlated models and study the phase diagram of experimentally relevant TMDs and other moiré superlattices. The political and strategic context of the project is set within the European Union's strong focus on quantum research and 2D materials, as evidenced by initiatives like the Graphene Flagship. Europe's investment in these technologies reflects their potential to revolutionize fields like information processing and energy efficiency, making moiré materials a crucial area of study for maintaining Europe's leadership in quantum technologies. Scientific Impact: Expanding the understanding of the underlying physics of correlated electron systems in moiré materials, leading to potential breakthroughs in superconductivity, topological states, nano-photonics and optoelectronics and quantum information. Technological Impact: Moiré materials could enable the design of new, highly tunable materials for quantum devices, particularly for quantum computing and low-energy electronics, addressing current technological limitations in these fields. Economic and Societal Impact: The ability to design and manipulate materials with quantum properties can lead to innovations in sectors like data transmission, storage, and energy-efficient technologies, potentially driving the next generation of quantum industries in Europe and beyond.

Data: CORDIS, © European Union