Symmetry breaking in twisted double bilayer graphene

By Minhao He, Yuhao Li, Jiaqi Cai, Yang Liu, Kenji Watanabe, Takashi Taniguchi, Xiaodong Xu, M. Yankowitz. 2020

194 citations recorded by the source corpus.

The flat bands that appear in some twisted van der Waals heterostructures provide a setting in which strong interactions between electrons lead to a variety of correlated phases 1 – 20 . In particular, heterostructures of twisted double bilayer graphene host correlated insulating states that can be tuned by both the twist angle and an external electric field 11 – 14 . Here, we report electrical transport measurements of twisted double bilayer graphene with which we examine the fundamental role of spontaneous symmetry breaking in its phase diagram. The metallic states near each of the correlated insulators exhibit abrupt drops in their resistivity as the temperature is lowered, along with associated nonlinear current–voltage characteristics. Despite qualitative similarities to superconductivity, the simultaneous reversals in the sign of the Hall coefficient point instead to spontaneous symmetry breaking as the origin of the abrupt resistivity drops, whereas Joule heating seems to underlie the nonlinear transport. Our results suggest that similar mechanisms are probably relevant across a broader class of semiconducting flat band van der Waals heterostructures. Transport measurements show that spontaneous symmetry breaking plays a crucial role in the correlated insulating and metallic states in twisted double bilayer graphene.

Subfields: Atomic and Molecular Physics, and Optics, Condensed Matter Physics, Materials Chemistry

View Paper: https://www.semanticscholar.org/paper/0f36eaee42ae06b114be5c6536cbb4acec082dc7

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In Atomic and Molecular Physics, and Optics

In Condensed Matter Physics

In Materials Chemistry

Citations in the corpus

Electrically tunable correlated and topological states in twisted monolayer–bilayer graphene (2020, background): “These features correspond closely with the CI and metallic states in tDBG [10–14], suggesting that at this twist angle the phase diagram of tMBG is similar to that of tDBG, with small differences arising owing to the absence”
Spontaneous fractional Chern insulators in transition metal dichalcogenide moiré superlattices (2021, background): “[16] Minhao He, Yuhao Li, Jiaqi Cai, Yang Liu, K.”