Mott insulating state and $d+id$ superconductivity in an ABC graphene trilayer

TL;DR

This paper investigates the electronic phases of ABC graphene trilayers, revealing a Mott insulator and dominant $d+id$ superconductivity driven by strong correlations, consistent with recent experimental observations.

Contribution

It provides a theoretical analysis of the Mott insulating state and $d+id$ superconductivity in ABC graphene trilayers using the Hubbard model, highlighting the role of electron correlations.

Findings

Mott insulator emerges beyond critical Uc at half-filling.

$d+id$ pairing dominates over other patterns in doped regions.

Superconductivity is enhanced by increasing on-site interaction.

Abstract

Motivated by the recently experimental reported signatures of the tunable Mott insulating state and superconductivity in an ABC graphene trilayer superlattice, we investigate the charge compressibility, the spin correlation, and the superconducting instability within the Hubbard model on a three-layer honeycomb lattice. It is found that an antiferromagnetically ordered Mott insulator emerges beyond a critical $U_c$ at half-filling, and the electronic correlation drives a $d+id$ superconducting pairing to be dominant over other pairing patterns in a wide doped region. The effective pairing interaction with $d+id$ pairing symmetry is strongly enhanced with the increasing of on-site interaction, and suppressed as the interlayer coupling strength increases. Our intensive numerical results demonstrate that the insulating state and superconductivity in an ABC graphene trilayer are driven by strong electric correlation, and it may offer an attractive systems to explore rich correlated behaviors.