• 文献标题:   Evidence for a fractional fractal quantum Hall effect in graphene superlattices
  • 文献类型:   Article
  • 作  者:   WANG L, GAO YD, WEN B, HAN Z, TANIGUCHI T, WATANABE K, KOSHINO M, HONE J, DEAN CR
  • 作者关键词:  
  • 出版物名称:   SCIENCE
  • ISSN:   0036-8075 EI 1095-9203
  • 通讯作者地址:   Columbia Univ
  • 被引频次:   54
  • DOI:   10.1126/science.aad2102
  • 出版年:   2015

▎ 摘  要

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.