Moiré domain-wall networks: a playground for correlated and topological phases

Chen-Hsuan Hsu^1*

¹Institute of Physics, Academia Sinica, Taipei, Taiwan

* Presenter:Chen-Hsuan Hsu, email:chenhsuan@as.edu.tw

We explore domain-wall networks in twisted bilayer graphene under an interlayer bias. In this talk, I will begin by introducing our bosonic model for interacting electrons in these networks [1-3]. The electron-electron interaction strength is tunable through sample design and gate voltages, which also control various correlation functions [1]. By including electron-phonon coupling, we obtain phase diagrams exhibiting density-wave and superconducting orders with electrically tunable phase transitions.

We then develop scattering operators to classify different processes in the network. Certain processes yield gapped bulk states with gapless edge modes [2], leading to (fractional) quantum anomalous Hall effects. We predict spectroscopic and transport signatures of these phases. The network models integrate concepts from the quantum anomalous Hall [2], quantum Hall [4], and quantum spin Hall [5] effects, demonstrating their broad applicability to topological and correlated systems.

If time permits, I will also discuss the formation of a two-dimensional spin helix in the presence of local magnetic moments [3], which exhibits magnon-induced singularities with observable features. These results establish the moiré domain-wall network as a versatile and electrically tunable platform for correlated electron phenomena.

*This work was financially supported by National Science and Technology Council (NSTC), Taiwan, through Grant No. NSTC-112-2112-M-001-025-MY3 and Academia Sinica, Taiwan through Grant No. AS-iMATE-114-12.

Reference:
[1] Hao-Chien Wang and CHH, 2D Mater. 11, 035007 (2024).
[2] CHH, Daniel Loss, and Jelena Klinovaja, Phys. Rev. B 108, L121409 (2023).
[3] Yung-Yeh Chang, Kazuma Saito, and CHH, Phys. Rev. Research 7, L032066 (2025).
[4] Charles L. Kane et al., Phys. Rev. Lett. 88, 036401 (2002).
[5] Jelena Klinovaja and Yarolav Tserkovnyak, Phys. Rev. B 90, 115426 (2014).

Keywords: Moiré bilayer systems, correlated electron systems, topological phases, fractional excitations, bosonization