Valleytronics in van der Waals Heterostructures: breAking inversion symmeTry with A TWIST (WHAT-A-TWIST)

• Applicants: Professorin Dr. Caterina Cocchi; Professor Dr. Giancarlo Soavi
• Subject Area: Experimental Condensed Matter Physics ; Theoretical Condensed Matter Physics
• Term: since 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 547611111

Valleytronics, i.e. the possibility to write, read, and store information in the band extrema (valleys) of semiconductors, is one of the most promising directions to satisfy the ever increasing demand of modern technologies. In particular, valleytronics based on two-dimensional materials and layered heterostructures provides unique advantages to address the challenges of miniaturization, power consumption, and speed thanks to ultrafast all-optical operations. From a fundamental viewpoint, it represents an exceptional platform to study symmetries and topology in atomically thin crystals. Unfortunately, the current state-of-the-art in valleytronics lacks a unified approach which hinders the development of this technology. With WHAT-A-TWIST, we aim to advance the field of valleytronics focusing on layered heterostructures of two-dimensional materials. Adopting a combination of quantum-mechanical ab initio methods and novel experimental techniques based on nonlinear spectroscopy, we will identify and produce non-centro-symmetric layered heterostructures formed by transition metal dichalcogenides with an even number of layers. We will disclose their electronic and optical properties, and demonstrate a new ultrafast and non-destructive method to detect valley polarization. This will enable us to achieve deterministic control over space inversion and time reversal symmetries, leading to tunable and engineered valley lifetimes. The knowledge gained in this project will significantly boost the development of valleytronics.

• DFG Programme: Research Grants