Robust Spin-1 Haldane Topology under Itinerant Doping
Abstract
We study itinerant hole doping of the spin-$1$ Haldane symmetry-protected topological (SPT) phase in two t--J chains coupled by ferromagnetic (FM) Hund exchange. Density-matrix renormalization group calculations show that string order, a finite spin gap, and the Haldane entanglement structure coexist over a broad doping range. Combined with entanglement-entropy scaling consistent with a single gapless charge mode, these results support a metallic doped Haldane SPT with a C1S0 low-energy description. At low doping, short-range charge correlations reduce the density of spin-1/2 defect rungs, whereas at larger doping their positions become nearly uncorrelated while their spins are collectively incorporated into the correlated spin sector. The doped Haldane SPT terminates in a fully spin-polarized FM phase, which forms a reentrant pocket at high doping in the global phase diagram. Dilute-limit analyses trace the two FM boundaries to spin--charge factorization at weak Hund coupling and to rung-triplet binding with reduced pair mobility at strong Hund coupling. Our results show how mobile carriers reorganize the Haldane spin structure while preserving its characteristic signatures.
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BibTeX
@misc{nishimoto2026robust,
title = {{Robust Spin-1 Haldane Topology under Itinerant Doping}},
author = {Satoshi Nishimoto},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.11591},
eprint = {2609.11591},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.11591},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Robust Spin-1 Haldane Topology under Itinerant Doping
AU - Satoshi Nishimoto
PY - 2026
DA - 2026/09/10
PB - arXiv
DO - 10.48550/arxiv.2609.11591
UR - https://arxiv.org/abs/2609.11591
AB - We study itinerant hole doping of the spin-$1$ Haldane symmetry-protected topological (SPT) phase in two t--J chains coupled by ferromagnetic (FM) Hund exchange. Density-matrix renormalization group calculations show that string order, a finite spin gap, and the Haldane entanglement structure coexist over a broad doping range. Combined with entanglement-entropy scaling consistent with a single gapless charge mode, these results support a metallic doped Haldane SPT with a C1S0 low-energy description. At low doping, short-range charge correlations reduce the density of spin-1/2 defect rungs, whereas at larger doping their positions become nearly uncorrelated while their spins are collectively incorporated into the correlated spin sector. The doped Haldane SPT terminates in a fully spin-polarized FM phase, which forms a reentrant pocket at high doping in the global phase diagram. Dilute-limit analyses trace the two FM boundaries to spin--charge factorization at weak Hund coupling and to rung-triplet binding with reduced pair mobility at strong Hund coupling. Our results show how mobile carriers reorganize the Haldane spin structure while preserving its characteristic signatures.
ER -