Haldane-Holstein model at fractional filling: Route to bosonic fractional Chern insulator and quantum anomalous Hall crystal
Abstract
Electron-phonon coupling is generally expected to suppress band topology, driving a topological band insulator into a trivial phase. Here we show that, using the prototypical Haldane-Holstein model at partial filling of a topological band, strong electron-phonon coupling can instead stabilize topological phases of matter. The electron-phonon coupling plays a double role: it generates the longer-range interactions that correlate the carriers and, in the attractive channel, also binds them into bosonic pairs. For spinful electrons, it pairs opposite spins into charge-2e bipolarons that form a bosonic fractional Chern insulator (FCI) at filling ν=1/2 with charge-e semionic excitations. Tuning the band topology and the coupling strength maps out a rich phase diagram containing this bosonic FCI, superconductors condensed at the M and K points, and several charge-ordered solids. For spin-polarized electrons, strong coupling instead stabilizes a C=2 quantum anomalous Hall crystal (QAHC) at ν=1/3. Electron-phonon coupling thus emerges as a route to, rather than an obstruction against, topology in partially filled Chern bands.
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BibTeX
@misc{wei2026haldaneholstein,
title = {{Haldane-Holstein model at fractional filling: Route to bosonic fractional Chern insulator and quantum anomalous Hall crystal}},
author = {Zezhu Wei and Ang-Kun Wu and Di Xiao and Shi-Zeng Lin},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.14191},
eprint = {2609.14191},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.14191},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Haldane-Holstein model at fractional filling: Route to bosonic fractional Chern insulator and quantum anomalous Hall crystal
AU - Zezhu Wei
AU - Ang-Kun Wu
AU - Di Xiao
AU - Shi-Zeng Lin
PY - 2026
DA - 2026/09/12
PB - arXiv
DO - 10.48550/arxiv.2609.14191
UR - https://arxiv.org/abs/2609.14191
AB - Electron-phonon coupling is generally expected to suppress band topology, driving a topological band insulator into a trivial phase. Here we show that, using the prototypical Haldane-Holstein model at partial filling of a topological band, strong electron-phonon coupling can instead stabilize topological phases of matter. The electron-phonon coupling plays a double role: it generates the longer-range interactions that correlate the carriers and, in the attractive channel, also binds them into bosonic pairs. For spinful electrons, it pairs opposite spins into charge-2e bipolarons that form a bosonic fractional Chern insulator (FCI) at filling ν=1/2 with charge-e semionic excitations. Tuning the band topology and the coupling strength maps out a rich phase diagram containing this bosonic FCI, superconductors condensed at the M and K points, and several charge-ordered solids. For spin-polarized electrons, strong coupling instead stabilizes a C=2 quantum anomalous Hall crystal (QAHC) at ν=1/3. Electron-phonon coupling thus emerges as a route to, rather than an obstruction against, topology in partially filled Chern bands.
ER -