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arXiv · 2310.10287

Ferromagnetic Haldane state and dimer multiplet state of quantum ferromagnets

Shin Miyahara·Isao Maruyama
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Abstract

We present a theory of the realization of a ferromagnetic Haldane state in a spin-2 bilinear-biquadratic spin system on an orthogonal-dimer chain. The coexistence of a ferromagnetic state and a Haldane state is due to the rigorous correspondence between the eigenstates of a spin-2 model and a spin-1/2 Heisenberg model; i.e., "eigensystem embedding." Numerical exact-diagonalization calculations indicate that the ground state in the model is a fractionally magnetized M = 3/4 Haldane state. Moreover, a ferromagnetic-dimer multiplet state is an exact ground state on a lattice, where the direct product of dimer singlet states is the ground state in a spin-1/2 Heisenberg model that includes one-, two-, and three-dimensional orthogonal-dimer lattices. Eigensystem embedding demonstrates that a quantum ferromagnet can be obtained for an arbitrary spin S >= 2 in any dimension and for any lattice in which anomalous ground states are realized in a spin-1/2 Heisenberg model.

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Shin Miyahara, Isao Maruyama. 2023-10-16. Ferromagnetic Haldane state and dimer multiplet state of quantum ferromagnets. https://doi.org/10.1103/physrevb.110.014433

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