Honeycomb Crystal in a Mass-Asymmetric Electron-Hole Bilayer
Abstract
A two-dimensional electron gas in a uniform neutralizing background forms a triangular Wigner crystal at low density. In a strongly mass-asymmetric electron-hole bilayer, localized heavy holes instead provide a nonuniform positive background that supports an electron crystal at densities two orders of magnitude higher than for a homogeneous electron gas in the same material. Here we show that correlated mobile electrons can overturn the preference for triangular order, stabilizing a honeycomb electron-hole crystal. Using the powerful real-space neural-network variational Monte Carlo in the Born-Oppenheimer limit with fixed holes, we find that increasing the density drives a transition from a triangular electron-hole crystal to a honeycomb crystal, which eventually melts into itinerant electrons coexisting with the honeycomb or the triangular hole lattice at fixed interlayer separation. Relative to triangular order, honeycomb order emerges when gains in electronic kinetic energy and electron-hole attraction outweigh its higher intralayer Coulomb repulsion, a threshold never reached in the rigid point-dipole model. Moreover, the honeycomb hole lattice supports paramagnetic, antiferromagnetic, and stripe-ordered spin states. Complex polarization indicates a metal-insulator transition, while the states on the honeycomb hole lattice are consistent with a stripe-ordered Dirac semimetal and paramagnetic or antiferromagnetic Mott insulators via mapping to the half-filled Hubbard model. We further propose a BLG/hBN/WS2-WSe2 heterostructure as a platform for the predicted honeycomb crystal, at an experimentally feasible density n∼1011 cm−2.
Related
- Asymmetric magnetoresistance in 3d-5d based La0.67Ca0.33MnO3/SrIrO3 bilayer: The role of unidirectional anisotropy
- Helicity-Selective Electron-Phonon Coupling Between PT-Partner States in 2H-bilayer MoS2
- Electron binding by charge disorder surrounding gapped bilayer graphene
- Electron--phonon cooling noise in monolayer and bilayer graphene
- Electric Field-Induced Hole- and Electron-Type Flat Bands in Twisted Double Bilayer Graphene
BibTeX
@misc{chai2026honeycomb,
title = {{Honeycomb Crystal in a Mass-Asymmetric Electron-Hole Bilayer}},
author = {Shengdu Chai and Wangqian Miao and Yuqiang Li and Lei Wang and Xi Dai and X. C. Xie},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.17030},
eprint = {2610.17030},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.17030},
}
RIS
TY - UNPB
TI - Honeycomb Crystal in a Mass-Asymmetric Electron-Hole Bilayer
AU - Shengdu Chai
AU - Wangqian Miao
AU - Yuqiang Li
AU - Lei Wang
AU - Xi Dai
AU - X. C. Xie
PY - 2026
DA - 2026/10/12
PB - arXiv
DO - 10.48550/arxiv.2610.17030
UR - https://arxiv.org/abs/2610.17030
AB - A two-dimensional electron gas in a uniform neutralizing background forms a triangular Wigner crystal at low density. In a strongly mass-asymmetric electron-hole bilayer, localized heavy holes instead provide a nonuniform positive background that supports an electron crystal at densities two orders of magnitude higher than for a homogeneous electron gas in the same material. Here we show that correlated mobile electrons can overturn the preference for triangular order, stabilizing a honeycomb electron-hole crystal. Using the powerful real-space neural-network variational Monte Carlo in the Born-Oppenheimer limit with fixed holes, we find that increasing the density drives a transition from a triangular electron-hole crystal to a honeycomb crystal, which eventually melts into itinerant electrons coexisting with the honeycomb or the triangular hole lattice at fixed interlayer separation. Relative to triangular order, honeycomb order emerges when gains in electronic kinetic energy and electron-hole attraction outweigh its higher intralayer Coulomb repulsion, a threshold never reached in the rigid point-dipole model. Moreover, the honeycomb hole lattice supports paramagnetic, antiferromagnetic, and stripe-ordered spin states. Complex polarization indicates a metal-insulator transition, while the states on the honeycomb hole lattice are consistent with a stripe-ordered Dirac semimetal and paramagnetic or antiferromagnetic Mott insulators via mapping to the half-filled Hubbard model. We further propose a BLG/hBN/WS_2-WSe_2 heterostructure as a platform for the predicted honeycomb crystal, at an experimentally feasible density n∼10^11 cm^−2.
ER -