Nonlinear Optical and Electrical Phenomena in Topological Semimetals

Project Information

NonlinearTopo

Grant agreement ID: 815869

DOI

10.3030/815869

Project closed

EC signature date 17 December 2018

Start date 1 January 2019

End date 30 June 2024

Funded under

• EXCELLENT SCIENCE - European Research Council (ERC)

Total cost

€ 1 721 706,00

EU contribution

€ 1 721 706,00

Coordinated by

WEIZMANN INSTITUTE OF SCIENCE
Israel

Periodic Reporting for period 4 - NonlinearTopo (Nonlinear Optical and Electrical Phenomena in Topological Semimetals)

Reporting period: 2023-07-01 to 2024-06-30

Summary of the context and overall objectives of the project

Over the past decade, topological materials have captivated scientific interest, primarily due to their unique surface states and intriguing electronic properties. However, the potential of these materials extends far beyond their surface characteristics. This project shifts the focus to an entirely new question: What novel phenomena and practical applications can topological materials offer?

Our research explores the nonlinear optical and electrical phenomena in topological semimetals. These phenomena could revolutionize technologies critical to society, such as green energy solutions, innovative solar energy harvesting, advanced photodetectors, and next-generation optoelectronic devices.

By delving into the fundamental physics of how band topology influences nonlinear light-matter interactions, we aim to unlock a deeper understanding of these materials. A key objective is to develop a diagnostic tool capable of analyzing nonlinear properties across a wide range of real materials. This tool will provide direct insights into the bulk topology of these materials, opening the door to new applications and advancing both science and technology.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

We developed a new theoretical framework to understand how materials respond to light and electromotive forces. This framework, which combines principles of quantum mechanics and classical physics, was the first to show how the quantum metric—a fundamental property of quantum systems—plays a key role in these nonlinear effects. Our predictions were confirmed experimentally in collaboration with a Singapore-based group, leading to the first-ever observation of the quantum metric through nonlinear transport measurements. This work has sparked a growing interest in using nonlinear resistance to explore the quantum metric in condensed matter physics.

Additionally, we discovered the topological electronic properties of DNA-like quantum materials and uncovered the overlooked role of orbitals in chirality-induced spin selectivity (CISS), a fascinating yet debated phenomenon. Our theoretical predictions were validated through experiments with chiral molecular devices in collaboration with a Florida-based group. These findings open new pathways to study magnetochiral interactions involving spin, charge, and chirality in complex chemical and biological systems, which are highly dynamic and nonlinear by nature.

Finally, our theoretical studies inspired a new method to detect orbital currents using a specially designed spin-orbit coupling layer. This innovation led to a patent application (US Patent App. 18/042,212) and has the potential to revolutionize the design of orbitronic devices, connecting fundamental discoveries to real-world applications.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

Our work advances the state of the art in multiple areas of condensed matter physics and materials science. By uncovering the critical role of the quantum metric in nonlinear phenomena, we have introduced a new dimension to the study of quantum materials. This research has already led to the first experimental measurement of the quantum metric, setting a benchmark for future explorations in the field.

In the domain of chirality-induced spin selectivity (CISS), we addressed long-standing debates by revealing the overlooked role of orbitals and providing experimentally verified predictions. This breakthrough extends the understanding of magnetochiral effects, particularly in complex systems such as chiral molecules and DNA-like quantum materials. These findings open avenues for exploring spin, charge, and chirality interactions in nonequilibrium and nonlinear systems, pushing the boundaries of what is currently understood about these phenomena.

Looking forward, the project is expected to deliver a set of diagnostic tools capable of probing nonlinear phenomena and directly measuring bulk topological properties in a wide range of materials. These tools will provide a practical framework for both fundamental research and technological innovation.

Additionally, our patented technique for detecting orbital currents is poised to make significant contributions to orbitronics—a rapidly emerging field focused on leveraging orbital degrees of freedom in device applications. By the end of the project, we expect to further develop and disseminate this technology, paving the way for its adoption in advanced optoelectronic and spintronic devices.

Nonlinear light-matter interaction in a topological material

Topological electrons in DNA