Hidden Staggered Superconducting Order in V2Se2O-Family Altermagnets
Abstract
η pairing describes a staggered superconducting condensate whose order parameter changes sign between neighboring unit cells while maintaining a uniform magnitude. Nearly four decades after its theoretical proposal by C. N. Yang, a material platform for stabilizing η pairing has remained elusive. Here, we reveal that altermagnetism, despite being pair breaking for conventional BCS pairing, naturally favors η-like pairing in V2Se2O-family altermagnets. Their valley-contrasting spin structure gives rise to oppositely spin-polarized, symmetry-related valleys centered at X=(π,0) and Y=(0,π), which form spin-singlet pairing partners separated by the commensurate momentum Q=(π,π), thereby favoring an η-like condensate. Self-consistent calculations demonstrate that the resulting η-like state remains robust over broad variations of chemical potential, hopping parameters, and Fermi-surface topology. To detect this hidden staggered order, we propose a phase-sensitive Josephson measurement with a uniform superconductor, where destructive interference suppresses single-Cooper-pair tunneling while preserving two-Cooper-pair processes. This constitutes a charge-4e-like Josephson response despite a bulk condensate composed of charge-2e Cooper pairs, providing a direct phase-sensitive signature of the otherwise elusive η-like condensate in V2Se2O-family altermagnets.
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BibTeX
@misc{wan2026hidden,
title = {{Hidden Staggered Superconducting Order in V2Se2O-Family Altermagnets}},
author = {Chun Yu Wan and Xiangxi Zhang and Fei Yang and Junwei Liu},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.22935},
eprint = {2610.22935},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.22935},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Hidden Staggered Superconducting Order in V2Se2O-Family Altermagnets
AU - Chun Yu Wan
AU - Xiangxi Zhang
AU - Fei Yang
AU - Junwei Liu
PY - 2026
DA - 2026/10/16
PB - arXiv
DO - 10.48550/arxiv.2610.22935
UR - https://arxiv.org/abs/2610.22935
AB - η pairing describes a staggered superconducting condensate whose order parameter changes sign between neighboring unit cells while maintaining a uniform magnitude. Nearly four decades after its theoretical proposal by C. N. Yang, a material platform for stabilizing η pairing has remained elusive. Here, we reveal that altermagnetism, despite being pair breaking for conventional BCS pairing, naturally favors η-like pairing in V_2Se_2O-family altermagnets. Their valley-contrasting spin structure gives rise to oppositely spin-polarized, symmetry-related valleys centered at X=(π,0) and Y=(0,π), which form spin-singlet pairing partners separated by the commensurate momentum Q=(π,π), thereby favoring an η-like condensate. Self-consistent calculations demonstrate that the resulting η-like state remains robust over broad variations of chemical potential, hopping parameters, and Fermi-surface topology. To detect this hidden staggered order, we propose a phase-sensitive Josephson measurement with a uniform superconductor, where destructive interference suppresses single-Cooper-pair tunneling while preserving two-Cooper-pair processes. This constitutes a charge-4e-like Josephson response despite a bulk condensate composed of charge-2e Cooper pairs, providing a direct phase-sensitive signature of the otherwise elusive η-like condensate in V_2Se_2O-family altermagnets.
ER -