Fractional Chern insulators versus nonmagnetic states in twisted bilayer MoTe2

Jiabin Yu, Jonah Herzog-Arbeitman, Minxuan Wang, Oskar Vafek, B. Andrei Bernevig, Nicolas Regnault

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7 Scopus citations

Abstract

Fractionally filled Chern bands with strong interactions may give rise to fractional Chern insulator (FCI) states, the zero-field analog of the fractional quantum Hall effect. Recent experiments have demonstrated the existence of FCIs in twisted bilayer MoTe2 without external magnetic fields - most robust at ν=-2/3 - as well as Chern insulators (CIs) at ν=-1. Although the appearance of both of these states is theoretically natural in an interacting topological system, experiments repeatedly observe nonmagnetic (or weakly magnetic) states (lacking FCIs) at ν=-1/3 and -4/3, a puzzling result, which has not been fully theoretically explained. In this paper, we perform Hartree-Fock and exact diagonalization calculations to test whether the standard MoTe2 moiré model with the (greatly varying) parameter values available in the literature can reproduce the nonmagnetic/weakly magnetic states at ν=-1/3 and -4/3 in unison with the FCI at ν=-2/3 and CI state at ν=-1. We focus on the experimentally relevant twist angles and, crucially, include remote bands. We find that the parameters proposed in Wang et al. [arXiv:2306.02501] can nearly capture the experimental phenomena at ν=-1/3,-2/3,-1,-4/3 simultaneously, although the predicted ground states at ν=-1/3 are still mostly FCIs and a larger dielectric constant ϵ>10 than is typical of hexagonal boron nitride (h-BN) substrate ϵ∼6 is required. Our results show the importance of remote bands in identifying the competing magnetic orders and lay the groundwork for further study of the realistic phase diagram.

Original languageEnglish (US)
Article number045147
JournalPhysical Review B
Volume109
Issue number4
DOIs
StatePublished - Jan 15 2024

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

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