Direct measurement of discrete valley and orbital quantum numbers in bilayer graphene

B. M. Hunt, J. I.A. Li, A. A. Zibrov, L. Wang, T. Taniguchi, K. Watanabe, J. Hone, C. R. Dean, M. Zaletel, R. C. Ashoori, A. F. Young

Research output: Contribution to journalArticle

39 Scopus citations

Abstract

The high magnetic field electronic structure of bilayer graphene is enhanced by the spin, valley isospin, and an accidental orbital degeneracy, leading to a complex phase diagram of broken symmetry states. Here, we present a technique for measuring the layer-resolved charge density, from which we directly determine the valley and orbital polarization within the zero energy Landau level. Layer polarization evolves in discrete steps across 32 electric field-tuned phase transitions between states of different valley, spin, and orbital order, including previously unobserved orbitally polarized states stabilized by skew interlayer hopping. We fit our data to a model that captures both single-particle and interaction-induced anisotropies, providing a complete picture of this correlated electron system. The resulting roadmap to symmetry breaking paves the way for deterministic engineering of fractional quantum Hall states, while our layer-resolved technique is readily extendable to other two-dimensional materials where layer polarization maps to the valley or spin quantum numbers.

Original languageEnglish (US)
Article number948
JournalNature communications
Volume8
Issue number1
DOIs
StatePublished - Dec 1 2017

All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Biochemistry, Genetics and Molecular Biology(all)
  • Physics and Astronomy(all)

Fingerprint Dive into the research topics of 'Direct measurement of discrete valley and orbital quantum numbers in bilayer graphene'. Together they form a unique fingerprint.

  • Cite this

    Hunt, B. M., Li, J. I. A., Zibrov, A. A., Wang, L., Taniguchi, T., Watanabe, K., Hone, J., Dean, C. R., Zaletel, M., Ashoori, R. C., & Young, A. F. (2017). Direct measurement of discrete valley and orbital quantum numbers in bilayer graphene. Nature communications, 8(1), [948]. https://doi.org/10.1038/s41467-017-00824-w