Speaker
Description
Moiré systems, with wide tunability, have provided a new platform for investigating strongly correlated physics, as demonstrated by a recent observation of a strange metal regime near the Mott transition in twisted WSe2 and a realization of flat-band ferromagnetism in twisted MoTe₂.
In this talk, I will first report our recent theoretical finding of two pseudogap states with Fermi arc and Fermi pocket in the triangular moir´e Hubbard model via the change of the displacement field at half-filling. These pseudogap phases, as proximate states of the Mott insulator, are non-Fermi liquids resulting from intrinsic strong correlations, which is elaborated by a comprehensive analysis of the density of states, quasiparticle weight, momentum distribution function and the poles and zeros of the interacting Green’s function. Moreover, we elaborate that the pseudogap phase with Fermi pockets is responsible for the strange metal behavior observed experimentally.
Then, I will discuss topological spin excitations out of the flat-band ferromagnetic ground state. We reveal that the itinerant topological magnons and spin excitons inherit their topology directly from the underlying electron bands, which is fundamentally different from local-moment systems. Their topological properties can be flexibly tuned by a perpendicular electric field and probed via the thermal Hall conductivity, providing a novel scheme for electrically controlled magnon topology in moiré flat-band systems.
Reference:
1. Y. Y. Zong, Z.L. Gu, and J.X. Li, Phys. Rev. X 16, 011005 (2026)
2. W. T. Zhou, Z.Y. Dong, Z.L. Gu and J.X. Li, Nat. Sci. Rev. 13, nwaf354 (2026)