Pseudogap in the lightly hole-doped triangular-lattice moir\'e Hubbard model

TL;DR

This study investigates the pseudogap phenomenon in a lightly hole-doped triangular-lattice moiré Hubbard model, revealing how magnetic interactions and frustration influence electronic properties using cluster perturbation theory and mean-field approximations.

Contribution

It introduces a combined CPT and GMFA approach to analyze the pseudogap and Fermi surface evolution in a frustrated triangular lattice Hubbard model, highlighting the effects of spin-orbital interactions.

Findings

Pseudogap behavior is strongly affected by magnetic correlations.

Geometric frustration enriches the pseudogap physics compared to square lattices.

Short-range magnetic order explains the evolution of the Fermi surface and pseudogap.

Abstract

The electronic structure of the lightly hole-doped triangular-lattice moir\'e Hubbard model is studied within cluster perturbation theory (CPT) using 13-site clusters for a fixed doping concentration $p=1/13$ varying the Coulomb parameter $U$ and the hopping phase parameter $\phi$ related to the spin-orbital interaction. We have also developed a rather simple generalized mean-field approximation (GMFA) containing the amplitude of the spin correlations as a free parameter to fit the CPT data.The evolution of the Fermi surface and the pseudogap with the parameters $\phi$ and $U$ is explained from the viewpoint of the short-range magnetic order. The geometric frustration and the additional model parameter related to the spin-orbital interaction result in a more rich physics of the pseudogap state compared to the case of a more conventional square lattice.