Quantum textures of the many-body wavefunctions in magic-angle graphene

Kevin P. Nuckolls, Ryan L. Lee, Myungchul Oh, Dillon Wong, Tomohiro Soejima, Jung Pyo Hong, Dumitru Călugăru, Jonah Herzog-Arbeitman, B. Andrei Bernevig, Kenji Watanabe, Takashi Taniguchi, Nicolas Regnault, Michael P. Zaletel, Ali Yazdani

Research output: Contribution to journalArticlepeer-review

28 Scopus citations

Abstract

Interactions among electrons create novel many-body quantum phases of matter with wavefunctions that reflect electronic correlation effects, broken symmetries and collective excitations. Many quantum phases have been discovered in magic-angle twisted bilayer graphene (MATBG), including correlated insulating1, unconventional superconducting2–5 and magnetic topological6–9 phases. The lack of microscopic information10,11 of possible broken symmetries has hampered our understanding of these phases12–17. Here we use high-resolution scanning tunnelling microscopy to study the wavefunctions of the correlated phases in MATBG. The squares of the wavefunctions of gapped phases, including those of the correlated insulating, pseudogap and superconducting phases, show distinct broken-symmetry patterns with a √3 × √3 super-periodicity on the graphene atomic lattice that has a complex spatial dependence on the moiré scale. We introduce a symmetry-based analysis using a set of complex-valued local order parameters, which show intricate textures that distinguish the various correlated phases. We compare the observed quantum textures of the correlated insulators at fillings of ±2 electrons per moiré unit cell to those expected for proposed theoretical ground states. In typical MATBG devices, these textures closely match those of the proposed incommensurate Kekulé spiral order15, whereas in ultralow-strain samples, our data have local symmetries like those of a time-reversal symmetric intervalley coherent phase12. Moreover, the superconducting state of MATBG shows strong signatures of intervalley coherence, only distinguishable from those of the insulator with our phase-sensitive measurements.

Original languageEnglish (US)
Pages (from-to)525-532
Number of pages8
JournalNature
Volume620
Issue number7974
DOIs
StatePublished - Aug 17 2023

All Science Journal Classification (ASJC) codes

  • General

Fingerprint

Dive into the research topics of 'Quantum textures of the many-body wavefunctions in magic-angle graphene'. Together they form a unique fingerprint.

Cite this