Bright dipolar excitons in twisted black phosphorus homostructures

TL;DR

This paper reports the discovery of a new type of bright infrared dipolar excitons in twisted black phosphorus structures, which exhibit high oscillator strength, tunable properties, and polarization dependence, offering a platform for studying correlated quantum phenomena.

Contribution

The study uncovers a novel class of bright dipolar excitons in twisted black phosphorus that are inherent to the reconstructed band structure, differing from traditional tunneling-based excitons.

Findings

Identified bright dipolar excitons with high oscillator strength in twisted BP

Demonstrated polarization dependence inherited from BP

Showed tunability of dipole moment and resonance energy with BP thickness

Abstract

Bright dipolar excitons, which contain electrical dipoles and have high oscillator strength, are an ideal platform for studying correlated quantum phenomena. They usually rely on carrier tunneling between two quantum wells or two layers to hybridize with nondipolar excitons to gain oscillator strength. In this work, we uncovered a new type of bright infrared dipolar exciton by stacking 90{\deg}-twisted black phosphorus (BP) structures. These excitons, inherent to the reconstructed band structure, exhibit high oscillator strength. Most importantly, they inherit the linear polarization from BP, which allows light polarization to be used to select the dipole direction. Moreover, the dipole moment and resonance energy can be widely tuned by the thickness of the BP. Our results demonstrate a useful platform for exploring tunable correlated dipolar excitons.