Emergence of Correlations in Alternating Twist Quadrilayer Graphene

TL;DR

This study investigates how varying twist angles in alternating twist quadrilayer graphene influence correlated insulating and superconducting phases, revealing angle-dependent emergence of these phenomena near the magic angle.

Contribution

It provides new experimental insights into the twist angle dependence of correlated phases in alternating twist multilayer graphene, especially near the magic angle.

Findings

Correlated insulators appear only at larger angles when hole doped.

Superconductivity is observed at smaller angles, with signs of correlated insulators weakening.

Results highlight the intermediate coupling regime where dispersion and interactions are comparable.

Abstract

Recently, alternating twist multilayer graphene (ATMG) has emerged as a family of moir\'e systems that share several fundamental properties with twisted bilayer graphene, and are expected to host similarly strong electron-electron interactions near the magic angle. Here, we study alternating twist quadrilayer graphene (ATQG) samples with twist angles of 1.96{\deg} and 1.52{\deg}, which are slightly removed from the magic angle of 1.68{\deg}. At the larger angle, we find signatures of correlated insulators only when the ATQG is hole doped, and no signatures of superconductivity, and for the smaller angle we find evidence of superconductivity, while signs of the correlated insulators weaken. Our results provide insight into the twist angle dependence of correlated phases in ATMG and shed light on the nature of correlations in the intermediate coupling regime at the edge of the magic angle range where dispersion and interaction are of the same order.