Three Reversed Spin Bound States in the Heisenberg Model of a Ferromagnetic Spin System.

New boundary bound states (BBS) are found of an integrable model with the magnetic impurities located at the edges of an open Heisenberg spin chain. These bound states carry the real energy and are formed by three or five imaginary modes of the rapidities. These imaginary modes of the rapidities give the non-zero antisymmetric wave functions and the moments of the centers of the bound states are zero. It means that these bound states are arisen by the magnetic impurities and localized at the edges of the correlated system. The Kondo screening occurs for the antiferromagnetic spin chain with the ferromagnetic impurities-electrons exchange interaction.New boundary bound states (BBS) are found of an integrable model with the magnetic impurities located at the edges of an open Heisenberg spin chain. These bound states carry the real energy and are formed by three or five imaginary modes of the rapidities. These imaginary modes of the rapidities give the non-zero antisymmetric wave functions and the moments of the centers of the bound states are zero. It means that these bound states are arisen by the magnetic impurities and localized at the edges of the correlated system. The Kondo screening occurs for the antiferromagnetic spin chain with the ferromagnetic impurities-electrons exchange interaction.

arXiv:cond-mat/9907057Journal of Physics Condensed MatterJan 1, 19990 citations

Bound and scattering states in the Heisenberg ferromagnet

Perez, Jose Fernando

Jan 1, 19730 citations

Ferromagnetic Haldane state and dimer multiplet state of quantum ferromagnets

Shin Miyahara, Isao Maruyama

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- $\frac{1}{2}$ 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- $\frac{1}{2}$ 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 $S\ensuremath{\geqq}2$ in any dimension and for any lattice in which anomalous ground states are realized in a spin- $\frac{1}{2}$ Heisenberg model.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-$\frac{1}{2}$ 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-$\frac{1}{2}$ 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 $S\ensuremath{\geqq}2$ in any dimension and for any lattice in which anomalous ground states are realized in a spin-$\frac{1}{2}$ Heisenberg model.

arXiv:2310.10287Physical review. B./Physical review. BJul 23, 20243 citations

Bound states in Heisenberg antiferromagnets

Stephen William Lovesey, Ewald Balcar

Physics Letters ASep 1, 19697 citations

2 The Free Energy of the Quantum Heisenberg Ferromagnet at Large Spin

Michele Correggi, Alessandro Giuliani

We consider the spin-S ferromagnetic Heisenberg model in three dimensions, in the absence of an external field. Spin wave theory suggests that in a suitable temperature regime the system behaves effectively as a system of non-interacting bosons (magnons). We prove this fact at the level of the specific free energy: if S → ∞ and the inverse temperature β → 0 in such a way that βS stays constant, we rigorously show that the free energy per unit volume converges to the one suggested by spin wave theory. The proof is based on the localization of the system in small boxes and on upper and lower bounds on the local free energy, and it also provides explicit error bounds on the remainder. 1We consider the spin-S ferromagnetic Heisenberg model in three dimensions, in the absence of an external field. Spin wave theory suggests that in a suitable temperature regime the system behaves effectively as a system of non-interacting bosons (magnons). We prove this fact at the level of the specific free energy: if S → ∞ and the inverse temperature β → 0 in such a way that βS stays constant, we rigorously show that the free energy per unit volume converges to the one suggested by spin wave theory. The proof is based on the localization of the system in small boxes and on upper and lower bounds on the local free energy, and it also provides explicit error bounds on the remainder. 1

Jan 1, 20126 citations

On the spin wave problem in the Heisenberg model of Ferromagnetism

J. Zittartz

The European Physical Journal AOct 1, 196521 citations

\frac{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-

\frac{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 $S\ensuremath{\geqq}2$ in any dimension and for any lattice in which anomalous ground states are realized in a spin-

\frac{1}{2}

Heisenberg model.