paper

Stabilization of zigzag order in NiPS via positive biquadratic interaction

arXiv:2603.25475 · doi:10.1103/l2t3-m78p

Abstract

Despite extensive research, the precise spin Hamiltonian of the van der Waals antiferromagnet NiPS -- which hosts a zigzag-ordered ground state -- remains debated. While consensus has emerged on ferromagnetic nearest-neighbor () and antiferromagnetic third-nearest-neighbor () Heisenberg interactions, recent studies suggest a biquadratic () exchange term may also play a role, though its estimated magnitude varies widely. To address this controversy, we perform density functional theory calculations and extract a positive biquadratic interaction with . Within the minimal -- model, we show that these parameters naturally stabilize zigzag ordering using minimally augmented spin-wave theory. Density-matrix renormalization group calculations further validate our extracted parameters as a reasonable description of the ground state. Although fully resolving the spin Hamiltonian of NiPS requires further investigation, our findings provide new insights into its biquadratic interaction.

11+11 pages, 8+2 figures

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