Physics Main Calendar

Understanding how symmetry, quantum geometry, and electronic correlations intertwine in two-dimensional systems is a central theme of this talk. I will introduce a new topological monolayer that hosts a dual quantum spin Hall insulator arising from the interplay between single-particle band topology and doping-tuned electronic instabilities [1,2]. The same material also exhibits a nonvolatile superlattice memory effect [3]: in a pristine monolayer, a long-period superlattice forms spontaneously and can be reversibly programmed ON and OFF through electrostatic tuning of low-energy electronic states, enabling switching between two lattice configurations whose unit-cell areas differ by nearly two orders of magnitude. These phenomena are established through a combination of linear and nonlinear transport, Raman spectroscopy, and STM measurements.

[1] J. Tang, Q. Ma, et al., Nature 628, 515 (2024).
[2] J. Li, J. Tang, Q. Ma, Y. Zhang, et al., arXiv:2506.18412.
[3] J. Tang, Q. Ma, et al., Nature (2026).