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arXiv · 2506.10254

Neel order, spin-spiral, and spin liquid ground state in frustrated three dimensional system CaMn2P2: A DFT+U and spin dynamics study

Bidyut Mallick·Sk. Soyeb Ali·S. K. Panda
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Abstract

We investigate the magnetic ground state and phase transitions in the frustrated three-dimensional system CaMn2P2 using first-principles calculations combined with spin-dynamics simulations. Our DFT+U calculations reveal that CaMn2P2 exhibits an indirect gap semiconducting ground state with a localized Mn2+ electronic configuration and negligible spin-orbit coupling effects. The computed exchange interactions show that the magnetic behavior is well described by a isotropic Heisenberg Hamiltonian. In this model, there are two major couplings: the NN interaction J1 couples the two Mn layers along the c-axis and next NN J2 is in the a-b plane where Mn ions form a hexagonal layer structure. Our results show that both J1 and J2 are antiferromagnetic in nature and as a consequence J2 induce frustration owing to the in-plane triangular geometry of the Mn-ions. The J1 is found to promote long-range antiferromagnetic order, while the J2 is responsible for spin canting and disorder. Our spin-wave analysis confirms that the system stabilizes a spin-spiral ground state with a propagation vector q = (1/6 , 1/6, 0) in agreement with neutron diffraction experiments. By tuning the J2/J1 ratio, we construct a phase diagram that reveals a transition from a collinear Neel antiferromagnetic state to different spin-spiral phases, and eventually to a disordered phase at large frustration. Atomistic spin-dynamics simulations capture the temperature evolution of the magnetism and reproduce the experimentally measured magnetic data with good accuracy. Furthermore, for large J2/J1, we identify a low temperature phase with slow spin relaxation and persistent fluctuations, suggesting a spin-liquid like state. Our study provides an understanding of frustration induced magnetism in CaMn2P2 and establishes it as a realization of J1-J2 model in three-dimensional lattice for exploring emergent magnetic phases.

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Bidyut Mallick, Sk. Soyeb Ali, S. K. Panda. 2025-06-12. Neel order, spin-spiral, and spin liquid ground state in frustrated three dimensional system CaMn2P2: A DFT+U and spin dynamics study. https://arxiv.org/abs/2506.10254

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