Magnetooptics of layered two-dimensional semiconductors and heterostructures: progress and prospects

TL;DR

This paper reviews the progress and future prospects of magnetooptical spectroscopy in layered 2D semiconductors and heterostructures, emphasizing insights into spin-valley physics and many-body excitonic phenomena.

Contribution

It provides a comprehensive overview of how magnetooptical techniques have advanced understanding of 2D materials' spin-valley physics and excitonic properties, highlighting recent discoveries and open challenges.

Findings

Deep insights into spin-valley physics of TMDCs

Discovery of interlayer excitons and phase control

Determination of exciton properties like mass and binding energy

Abstract

Beginning with the 'conventional' two-dimensional (2D) quantum wells (QWs) based on III-V and II-VI semiconductors in the 1970s, to the recent atomically-thin sheets of van der Waals materials such as 2D semiconducting transition metal dichalcogenides (TMDCs) and 2D magnets, the research in 2D materials is continuously evolving and providing new challenges. Magnetooptical spectroscopy has played a significant role in this area of research, both from fundamental physics and technological perspectives. A major challenge in 2D semiconductors such as TMDCs is to understand their spin-valley-resolved physics, and their implications in quantum computation and information research. Since the discovery of valley Zeeman effects, deep insights into the spin-valley physics of TMDCs and their heterostructures has emerged through magnetooptical spectroscopy. In this perspective, we highlight the role of magnetooptics in many milestones such as the discovery of interlayer excitons, phase control between coherently-excited valleys, determination of exciton-reduced masses, Bohr radii and binding energies, physics of the optically-bright and dark excitons, trions, other many-body species such as biexcitons and their phonon replicas in TMDC monolayers. The discussion accompanies open questions, challenges and future prospects in the field including comments on the magnetooptics of van der Waals heterostructures involving TMDCs and 2D magnets.