Nature of the 1/3 Magnetization Plateau in Spin-1/2 Kagome Antiferromagnets

2025/04/25 by He, Li-Wei, Wang, Xinzhe, Yu, Shun-Li +1 · 1 citation
#FOS: Physical sciences #Strongly Correlated Electrons (cond-mat.str-el)

paper · doi:10.48550/arxiv.2504.18480

Abstract

We investigate the origin of the 1/3 magnetization plateau in the S=1/2 kagome antiferromagnetic Heisenberg model using the variational Monte Carlo and exact diagonalization methods, to account for the recent experimental observations in YCu₃(OH)_6+xBr_3-x and YCu₃(OD)_6+xBr_3-x. We identify three degenerate valence-bond-solid (VBS) states forming a √(3) × √(3) unit cell. These states exhibit David-star patterns in the spin moment distribution with only two fractional values -1/3 and 2/3, and are related through translational transformations. While the spin correlations in these VBS states are found to be short-range, resembling a quantum spin liquid, we show that they have a vanishing topological entanglement entropy and thus are topologically trivial many-body states. Our theoretical results provide strong evidence that the 1/3 magnetization plateau observed in recent experiments arises from these √(3) × √(3) VBS states with fractional spin moments.

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• Recent progress in quantum spin liquids, fractional magnetization plateaus, and unconventional superconductivity in kagome lattices

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