B51.00012. Topological flat bands without magic angles in massive twisted bilayer graphenes

Presented by: Srivani Javvaji


Abstract

We show that in massive twisted bilayer graphenes, isolated nearly flat bands below a threshold bandwidth Wc are expected for continuous small twist angles up to a critical θc depending on the flatness of the original bands and the interlayer coupling strength. The phase diagram of finite valley Chern numbers of the isolated moire bands expands with increasing difference between the sublattice selective interlayer tunneling parameters. The valley contrasting circular dichroism for interband optical transitions is constructive near 0° and destructive near 60° alignments and can be tuned through electric field and gate driven polarization of the mini-valleys. Combining massive Dirac materials with various intrinsic gaps, Fermi velocities, interlayer tunneling strengths suggest optimistic prospects of increasing θc and achieving correlated states with large U/W effective interaction versus bandwidth ratios. *This work was mainly supported by Samsung Science and Technology Foundation under project no. SSTF-BA1802-06, Korean NRF under grant number NRF-2016R1A2B4010105, the 2017 Research Fund of the University of Seoul, and NSFC (No. 11604166). This work was partly performed at the Aspen Center for Physics, which is supported by National Science Foundation grant PHY-1607611.

Authors

  • Srivani Javvaji
  • Jin-Hua Sun
  • Jeil Jung


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