Pseudogap with Fermi arcs and Fermi pockets in half-filled twisted transition metal dichalcogenides

TL;DR

This paper theoretically explores the evolution of correlated electronic states in half-filled twisted transition metal dichalcogenides, revealing pseudogap phases, Fermi arcs, pockets, and a transition to a Fermi liquid driven by electron correlations.

Contribution

It provides a detailed theoretical analysis of the ground state evolution in the moiré Hubbard model for twisted WSe2, identifying pseudogap states and Fermi surface reconstructions.

Findings

Identification of pseudogap states with Fermi arcs and pockets.

Demonstration of band structure reconstruction driven by electron correlations.

Prediction of a Lifshitz transition to a Fermi liquid.

Abstract

Twisted transition metal dichalcogenides are a new platform for realizing strongly correlated physics with high tunability. Recent transport experiments [A. Ghiotto et al. Nature 597, 345 (2021)] have reported the bandwidth-driven evolution of a Mott insulator to a strange metal behavior via the tuning of a displacement field in twisted $\mathrm{WSe_2}$ fixed at half filling. However, the nature of the correlated states and the related Mott physics involved in the whole process remain to be determined. Here, we unveil theoretically the evolution of the ground state of the half-filled $\mathrm{moir\acute{e}}$ Hubbard model as applied to $\mathrm{tWSe_2}$, transiting from a pseudogap state with Fermi arcs to a $120^\circ$ Ne$\acute{\mathrm{e}}$l ordered Mott insulator, then to another pseudogap state with Fermi pockets, and eventually to a Fermi liquid via a Lifshitz transition. The pseudogap phases are definitely identified by the vanishing of quasiparticle weights over parts of the Fermi surface, with the remaining parts forming disconnected Fermi arcs or pockets with well-defined quasiparticles. We demonstrate that the Fermi arc/pocket results from the electronic band structure reconstruction driven by electron correlations, marked by the coexistence of the poles and zeros of the single-particle Green's function. This work reveals the fundamental aspects of the Mottness in $\mathrm{moir\acute{e}}$ system and will stimulate the direct probes of the underling physice beyond transports via the angle-resolved photoemission spectroscopy and scanning tunneling microscopy.