Publication Date:
2016-01-20
Description:
The Hofstadter energy spectrum provides a uniquely tunable system to study emergent topological order in the regime of strong interactions. Previous experiments, however, have been limited to low Bloch band fillings where only the Landau level index plays a role. We report measurements of high-mobility graphene superlattices where the complete unit cell of the Hofstadter spectrum is accessible. We observed coexistence of conventional fractional quantum Hall effect (QHE) states together with the integer QHE states associated with the fractal Hofstadter spectrum. At large magnetic field, we observed signatures of another series of states, which appeared at fractional Bloch filling index. These fractional Bloch band QHE states are not anticipated by existing theoretical pictures and point toward a distinct type of many-body state.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Wang, Lei -- Gao, Yuanda -- Wen, Bo -- Han, Zheng -- Taniguchi, Takashi -- Watanabe, Kenji -- Koshino, Mikito -- Hone, James -- Dean, Cory R -- New York, N.Y. -- Science. 2015 Dec 4;350(6265):1231-4. doi: 10.1126/science.aad2102.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Mechanical Engineering, Columbia University, New York, NY 10027, USA. Kavli Institute at Cornell for Nanoscale Science, Ithaca, NY 14853, USA. ; Department of Mechanical Engineering, Columbia University, New York, NY 10027, USA. ; Department of Physics, Columbia University, New York, NY 10027, USA. ; National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan. ; Department of Physics, Tohoku University, Sendai 980-8578, Japan. ; Department of Physics, Columbia University, New York, NY 10027, USA. cdean@phys.columbia.edu.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/26785484" target="_blank"〉PubMed〈/a〉
Print ISSN:
0036-8075
Electronic ISSN:
1095-9203
Topics:
Biology
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Chemistry and Pharmacology
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Computer Science
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Medicine
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Natural Sciences in General
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Physics
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