Characterizing and manipulating the circular polarization of light is central to numerous emerging technologies, including spintronics and quantum computing. Separately, monolayer tungsten disulfide (WS2) is a versatile material that has demonstrated promise in a variety of applications, including single photon emitters and valleytronics. Here, we demonstrate a method to tune the photoluminescence (PL) intensity (factor of x161), peak position (38.4meV range), circular polarization (39.4% range), and valley polarization of a Bi2Se3-WS2 2D heterostructure using a low-power laser (0.762uW) in ambient. Changes are spatially confined to the laser spot, enabling submicron (814nm) features, and are long-term stable (>334 days). PL and valley polarization changes can be controllably reversed through laser exposure in vacuum, allowing the material to be erased and reused. Atmospheric experiments and first-principles calculations indicate oxygen diffusion modulates the exciton radiative vs. non-radiative recombination pathways, where oxygen absorption leads to brightening, and desorption to darkening.
@article{arxiv.2202.07495,
title = {Laser-patterned submicron Bi2Se3-WS2 pixels with tunable circular polarization at room temperature},
author = {Zachariah Hennighausen and Darshana Wickramaratne and Kathleen M. McCreary and Bethany M. Hudak and Todd Brintlinger and Hsun-Jen Chuang and Mehmet A. Noyan and Berend T. Jonker and Rhonda M. Stroud and Olaf M. vant Erve},
journal= {arXiv preprint arXiv:2202.07495},
year = {2022}
}