Finite-momentum pairing and magnetic halos in a spin-imbalanced Holstein model
Abstract
Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) superconductivity, Cooper pairing at finite-momentum driven by spin imbalance, remains difficult to study numerically in two dimensions. The fermion sign problem in the spin-imbalanced attractive Hubbard model severely limits quantum Monte Carlo access to the low temperatures where pairing correlations are most pronounced. We show that the Holstein model, in which the effective attraction is retarded by phonon dynamics, strongly suppresses sign fluctuations under spin imbalance, enabling unbiased determinant quantum Monte Carlo simulations deep in this regime. With increasing magnetization, zero-momentum pairing evolves into finite-momentum FFLO pairing, evidenced by oscillating real-space pair correlations and a shift of the pairing susceptibility peak to finite Q⃗. The finite-momentum susceptibility substantially exceeds its zero-momentum value. At high density n ∼ 0.875, near magnetization m ≈ 1−n where the majority-spin density approaches half filling, FFLO pairing coexists with checkerboard charge-density-wave order at short range, while staggered longitudinal spin correlations emerge as a magnetic halo at larger distances. These spatial textures provide experimentally accessible signatures of finite-momentum pairing and motivate cold-atom realizations of FFLO physics.
Related
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BibTeX
@misc{feng2026finitemomentum,
title = {{Finite-momentum pairing and magnetic halos in a spin-imbalanced Holstein model}},
author = {Chunhan Feng and George Batrouni and Richard Scalettar},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.03678},
eprint = {2610.03678},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.03678},
}
RIS
TY - UNPB
TI - Finite-momentum pairing and magnetic halos in a spin-imbalanced Holstein model
AU - Chunhan Feng
AU - George Batrouni
AU - Richard Scalettar
PY - 2026
DA - 2026/10/02
PB - arXiv
DO - 10.48550/arxiv.2610.03678
UR - https://arxiv.org/abs/2610.03678
AB - Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) superconductivity, Cooper pairing at finite-momentum driven by spin imbalance, remains difficult to study numerically in two dimensions. The fermion sign problem in the spin-imbalanced attractive Hubbard model severely limits quantum Monte Carlo access to the low temperatures where pairing correlations are most pronounced. We show that the Holstein model, in which the effective attraction is retarded by phonon dynamics, strongly suppresses sign fluctuations under spin imbalance, enabling unbiased determinant quantum Monte Carlo simulations deep in this regime. With increasing magnetization, zero-momentum pairing evolves into finite-momentum FFLO pairing, evidenced by oscillating real-space pair correlations and a shift of the pairing susceptibility peak to finite Q⃗. The finite-momentum susceptibility substantially exceeds its zero-momentum value. At high density n ∼ 0.875, near magnetization m ≈ 1−n where the majority-spin density approaches half filling, FFLO pairing coexists with checkerboard charge-density-wave order at short range, while staggered longitudinal spin correlations emerge as a magnetic halo at larger distances. These spatial textures provide experimentally accessible signatures of finite-momentum pairing and motivate cold-atom realizations of FFLO physics.
ER -