A recent experiment has observed a series of quantum-spin-Hall effects in moiré MoTe. Among them, the vanishing Hall signal at the filling factor ν = 3 implies a possible realization of a time-reversal pair of even-denominator fractional Chern insulators. Inspired by this discovery, we numerically investigate whether a robust incompressible quantum-Hall liquid can be stabilized in the half-filled Chern band of twisted MoTe bilayers. We use the continuum model with parameters relevant to twisted MoTe bilayers and obtain three consecutive nearly flat Chern bands with the same Chern number. Crucially, when the second moiré miniband is half-filled, signatures of a non-Abelian fractional quantum-Hall state are found via exact diagonalization calculations, including a stable six-fold ground-state degeneracy that grows more robust with the lattice size and is consistent with an even-denominator fractional Chern insulator state. Our results signal the potential of realizing the non-Abelian state at zero magnetic field in twisted bilayer MoTe at the fractional hole filling of 3/2.
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Robust non-Abelian even-denominator fractional Chern insulator in twisted bilayer MoTe.
Nat Commun
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Department of Physics and Astronomy, California State University Northridge, Northridge, California, USA.
A recent experiment has observed a series of quantum-spin-Hall effects in moiré MoTe. Among them, the vanishing Hall signal at the filling factor ν = 3 implies a possible realization of a time-reversal pair of even-denominator fractional Chern insulators. Inspired by this discovery, we numerically investigate whether a robust incompressible quantum-Hall liquid can be stabilized in the half-filled Chern band of twisted MoTe bilayers.
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We investigate the moiré band structures and a possible even-denominator fractional quantum Hall state in small angle twisted bilayer MoTe_{2}, using combined large-scale local basis density functional theory calculation and continuum model exact diagonalization. Via large-scale first-principles calculations at θ=1.89°, we find a sequence of C=1 (Chern number in the K valley) moiré Chern bands in analogy to Landau levels.
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Article Synopsis
- The even-denominator fractional quantum Hall (FQH) states, specifically ν=5/2 and ν=7/2, are predicted to contain exotic non-Abelian quasiparticles, which could have significant implications in quantum computing.
- Previous thermal conductance measurements have provided evidence for the non-Abelian characteristics of the ν=5/2 state, but there were concerns about thermal equilibration among edge modes impacting results.
- The paper presents a new method of measuring thermal Hall conductance for both the ν=5/2 and ν=7/2 states, confirming their non-Abelian nature and the presence of a Majorana edge mode, while also prompting further theoretical investigations due to discrepancies with existing numerical predictions.
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