Establish the nature of the competing state at filling one-seventh

Establish whether the enhanced charge correlations observed at filling \(\nu=1/7\) represent Bragg peaks associated with a charge-density wave, a Wigner crystal, or another additional charge, spin, or bond-ordered state by using larger systems and finite-size scaling.

Background

At ν=1/7\nu=1/7, the computationally accessible clusters do not display the ground-state pattern expected for a fractional quantum spin Hall phase. The momentum occupation is strongly nonuniform and the charge structure factor has modest enhancements along Brillouin-zone diagonals, but the available finite systems are too small to distinguish a crystalline phase from short-range correlations.

Because the parent stDDW state already breaks translation symmetry through hidden bond order, the competing phase could involve charge, spin, or additional bond order rather than a conventional Wigner crystal. Larger clusters and finite-size scaling are required to resolve this question.

References

Though they identify the dominant short-range correlations, one needs to scale to larger system sizes to more carefully establish whether these features are Bragg peaks associated with a crystalline state such as a CDW or a Wigner crystal.

Fractional quantum spin Hall crystals from hidden density-wave order  (2609.19638 - Shammami et al., 17 Sep 2026) in Section IV, subsection \(\nu=1/7\), and Section V