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

Principal investigators

  1. Caterina Cocchi, Friedrich Schiller University Jena [webpage]
  2. Giancarlo Soavi, Friedrich Schiller University Jena [webpage]

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Abstract

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 the valley polarization. This will enable us to achieve deterministic control over space inversion and time reversal symmetries, leading to tunable and engineered valley lifetimes.