@article{b9c405a14ece4e9d8f0a3daaf3fbf065,
title = "Observation of fractional Chern insulators in a van der Waals heterostructure",
abstract = "Topologically ordered phases are characterized by long-range quantum entanglement and fractional statistics rather than by symmetry breaking. First observed in a fractionally filled continuum Landau level, topological order has since been proposed to arise more generally at fractional fillings of topologically nontrivial Chern bands. Here we report the observation of gapped states at fractional fillings of Harper-Hofstadter bands arising from the interplay of a magnetic field and a superlattice potential in a bilayer graphene-hexagonal boron nitride heterostructure. We observed phases at fractional filling of bands with Chern indices C = −1, ±2, and ±3. Some of these phases, in C = −1 and C = 2 bands, are characterized by fractional Hall conductance-that is, they are known as fractional Chern insulators and constitute an example of topological order beyond Landau levels.",
author = "Spanton, {Eric M.} and Zibrov, {Alexander A.} and Haoxin Zhou and Takashi Taniguchi and Kenji Watanabe and Zaletel, {Michael P.} and Young, {Andrea F.}",
note = "Funding Information: We thank M. Barkeshli, A. Bernevig, C. Dean, and R. Mong for discussions and J. Jaroszynski and M. Yankowitz for experimental assistance. Funding: Numerical simulations were performed on computational resources supported by the Princeton Institute for Computational Science and Engineering using iDMRG code developed with R. Mong and the TenPy Collaboration. E.M.S. acknowledges the support of the Elings Fellowship. K.W. and T.T. acknowledge support from the Elemental Strategy Initiative conducted by the Ministry of Education, Culture, Sports, Science and Technology (MEXT) of Japan and Japan Society for the Promotion of Science KAKENHI grant JP15K21722. Measurements were performed at the National High Magnetic Field Laboratory, which is supported by NSF Cooperative Agreement DMR-1157490 and the state of Florida. Magnetocapacitance measurements were funded by the NSF under grant DMR-1654186. A portion of the nanofabrication and transport measurements were funded by the U.S. Army Research Office under proposal 69188PHH. A.F.Y. acknowledges the support of the David and Lucile Packard Foundation. Author contributions: A.A.Z., E.M.S., and H.Z. performed the measurements. A.A.Z. fabricated the device. T.T. and K.W. provided hBN single crystals. M.P.Z. performed calculations. E.M.S., A.A.Z., M.P.Z., and A.F.Y. wrote the manuscript with input from all coauthors. Competing interests: None declared. Data and materials availability: Experimental data files are available from the Open Science Framework at http://osf.io/7qckf/. Publisher Copyright: {\textcopyright} 2018 American Association for the Advancement of Science. All Rights Reserved.",
year = "2018",
doi = "10.1126/science.aan8458",
language = "English (US)",
volume = "360",
pages = "62--66",
journal = "Science",
issn = "0036-8075",
publisher = "American Association for the Advancement of Science",
number = "6384",
}