Spinless and Spinful Charge Excitations in Moiré Fractional Chern Insulators

Fractionally charged elementary excitations, the quasielectron and quasihole, are hallmarks of the fractional Chern insulator. We observe that spontaneous spin polarization in twisted MoTe2 leads to multiple species of low-energy quasiparticles distinguished by their spin quantum numbers. Through large-scale exact diagonalization calculations, we investigate the nature of these excitations and develop a method to extract their energetic properties. Focusing on θ=3.7° and filling factor ν=-2/3 relevant to recent experiments, we show that spin-preserving (spinless) charge excitations have smaller gap than spin-flipping (spinful) excitations with and without band mixing. This result is in qualitative agreement with the measured magnetic field dependence of the transport gaps. Beyond spinless and spinful quasiparticle gaps, we extract the full quasielectron and quasihole “band structure” and find significant dispersion with emergent magnetic translation symmetry—a fundamental departure from the immobile excitations of the quantum Hall fluid. Our work establishes a framework for computing the properties of elementary excitations in fractional Chern insulators.