Observation of quadratic magnetoresistance in twisted double bilayer graphene

Magnetoresistance (MR) provides rich information about Fermi surface, carrier scatterings, and exotic phases for a given electronic system. Here, we report a study of the magnetoresistance for the metallic states in twisted double bilayer graphene (TDBG). We observe quadratic magnetoresistance in both Moire valence band (VB) and Moire conduction band (CB). The scaling analysis shows validity of Kohler's rule in the Moire valence band. On the other hand, the quadratic magnetoresistance appears near the halo structure in the Moire conduction band, and it violates Kohler's rule, demonstrating the MR scaling related to band structure in TDBG. We also propose an alternative scaling near the halo structure. Further analysis implies that the observed quadratic magnetoresistance and alternative scaling in conduction band are related to the halo boundary. Our results may inspire investigation on MR in twisted 2D materials and provide new knowledge for MR study in condensed matter physics.

Automated summary

In this study, we report the magnetoresistance of metallic states in twisted double bilayer graphene (TDBG). Quadratic magnetoresistance is observed in both Moire valence band and Moire conduction band. The scaling analysis shows the validity of Kohler's rule in the Moire valence band, while the presence of quadratic magnetoresistance near the halo structure in the Moire conduction band violates Kohler's rule, demonstrating a different scaling related to band structure in TDBG. An alternative scaling near the halo structure is proposed. Further analysis suggests that the observed quadratic magnetoresistance and alternative scaling in the conduction band are related to the halo boundary.