Direct measurement of discrete valley and orbital quantum numbers in bilayer graphene
- Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States). Dept. of Physics; Columbia Univ., New York, NY (United States). Dept. of Physics; Carnegie Mellon Univ., Pittsburgh, PA (United States). Dept. of Physics
- Columbia Univ., New York, NY (United States). Dept. of Physics
- Univ. of California, Santa Barbara, CA (United States). Dept. of Physics
- Columbia Univ., New York, NY (United States)
- National Inst. for Materials Science (NIMS), Tsukuba (Japan)
- Microsoft Research, Santa Barbara, CA (United States). Station Q
- Massachusetts Inst. of Tech., Cambridge, MA (United States)
- Massachusetts Inst. of Tech., Cambridge, MA (United States); Univ. of California, Santa Barbara, CA (United States)
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.
- Research Organization:
- Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES)
- Grant/Contract Number:
- FG02-08ER46514
- OSTI ID:
- 1529936
- Alternate ID(s):
- OSTI ID: 1545718
- Journal Information:
- Nature Communications, Vol. 8, Issue 1; ISSN 2041-1723
- Publisher:
- Nature Publishing GroupCopyright Statement
- Country of Publication:
- United States
- Language:
- English
Web of Science
Similar Records
Carrier dynamics and spin–valley–layer effects in bilayer transition metal dichalcogenides
Valley-Coherent Quantum Anomalous Hall State in AB-Stacked Bilayers