Two-dimensional (2D) materials offer a rich platform for studying quantum phenomena since their properties can be profoundly altered through defect manipulation, heterostructure stacking, and lattice alignment. I will discuss several examples that highlight the remarkable potential of engineered two-dimensional (2D) materials to explore novel quantum phases of matter using scanning tunneling microscopy (STM). I will first discuss the interplay between quantum confinement and strong correlation in 1D twin-boundary defects of semiconducting 1H-MoSe2 which reveal evidence of spin-charge fractionalization due to the formation of a 1D Tomonaga-Luttinger liquid.1 I will also discuss our recent work on visualization and manipulation of 1D chiral edge states in a moiré quantum anomalous Hall (QAH) insulator of twisted monolayer-bilayer graphene (tMBLG).2,3 Here spectroscopic mapping allows us to directly identify QAH edge states, while combining electrostatic gating and tip-induced doping enables us to create and manipulate QAH edge states on-demand. I will conclude by providing a glimpse into new avenues of 2D materials engineering involving advanced atomically-precise characterization in the growing field of quantum materials.
[1] Zhu, T, Ruan, W, Wang, Y.-Q. Tsai, H.-Z., Wang, S., Zhang, C., Wang, T., Liou, F., Watanabe, K., Taniguchi, T., Neaton, J. B., Weber-Bargioni, A., Zettl, A., Qiu, Z. Q., Zhang, G., Wang, F., Moore, J. E. & Crommie, M. F. Imaging gate-tunable Tomonaga–Luttinger liquids in 1H-MoSe2 mirror twin boundaries. Nat. Mater. 21, 748–753 (2022)
[2] Zhang, C, Zhu, T., Kahn, S., Soejima, T., Watanabe, K., Taniguchi, T., Zettl, A., Wang, F., Zaletel, M. P. & Crommie, M. F. Visualizing and manipulating chiral edge states in a moiré quantum anomalous Hall insulator. Preprint at https://doi.org/10.48550/arXiv.2212.03380 (2022)
[3] Zhang, C., Zhu, T., Soejima, T., Kahn, S., Watanabe, K., Taniguchi, T., Zettl, A., Wang, F., Zaletel, M. P. & Crommie, M. F. Local spectroscopy of gate-switchable Chern insulating states in twisted monolayer-bilayer graphene. Nat. Commun., 14, 3595 (2023)