Weak localization on moir\'e superlattice in twisted double bilayer graphene

TL;DR

This study investigates how weak localization effects in twisted double bilayer graphene vary with twist angle, revealing that intervalley scattering increases as the moiré superlattice's Brillouin zone shrinks, affecting electronic properties.

Contribution

It provides the first detailed analysis of twist angle dependence of weak localization in TDBG, linking it to changes in intervalley scattering within the moiré superlattice.

Findings

Intervalley scattering ratio decreases with increasing twist angle.

Weak localization occurs within the moiré superlattice's reconstructed Brillouin zone.

Enhanced intervalley scattering is linked to the reduction of intervalley distance.

Abstract

Moir\'e superlattice created by twist stacking has multiple physical properties. These physical properties depend on the twist angle, hence investigation of the twist angle dependency is important for the deep understanding of physical phenomena in moir\'e superlattice. In this work, negative magnetoresistance owing to weak localization (WL) was investigated in twisted double bilayer graphene (TDBG) as a function of the twist angle. The ratio of the intervalley scattering time to the intravalley scattering time, estimated using the WL formula for bilayer graphene, tended to decrease as the twist angle increased. This feature is qualitatively explained by the enhancement of intervalley scattering due to the reduction of the intervalley distance in the moir\'e Brillouin zone (BZ) of the TDBG. This indicates that WL in the TDBG occurs for the moir\'e superlattice with the reconstructed BZ.