Effect of Single-Ion Anisotropy on Stability of Quantum and Thermal Entanglement in a Mixed-Spin Heisenberg Trimer

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Main Authors: Vargová, Hana, Strečka, Jozef
Format: Preprint
Published: 2025
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author Vargová, Hana
Strečka, Jozef
author_facet Vargová, Hana
Strečka, Jozef
contents The effect of uniaxial single-ion anisotropy on quantum entanglement is rigorously quantified using negativity in a mixed spin-($1$,$1/2$,$1$) Heisenberg trimer, accounting for different exchange coupling constants between identical and distinct spins. Bipartite negativities between the single-spin entity and the remaining spin dimer are analyzed alongside the global tripartite negativity (gTN) of the whole trimer under the effect of an external magnetic field and both easy-axis and easy-plane types of single-ion anisotropy. Interestingly, the single-ion anisotropy significantly influences the degree of entanglement by altering the stability regions of energetically preferred ground states and it may also introduce additional phases in the overall ground-state phase diagram. Moreover, it is demonstrated that within specific ground states, the degree of entanglement primarily depends on the strength of single-ion anisotropy, altering the respective probability amplitudes of the corresponding eigenvectors. Finally, the thermal stability of entanglement is discussed in detail, including the emergence of a peculiar local minimum at finite temperatures. The obtained theoretical results may offer deeper insights into bipartite and tripartite entanglement in trimetallic Ni$^{2+}$-Cu$^{2+}$-Ni$^{2+}$ molecular compounds.
format Preprint
id arxiv_https___arxiv_org_abs_2509_01451
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Effect of Single-Ion Anisotropy on Stability of Quantum and Thermal Entanglement in a Mixed-Spin Heisenberg Trimer
Vargová, Hana
Strečka, Jozef
Quantum Physics
The effect of uniaxial single-ion anisotropy on quantum entanglement is rigorously quantified using negativity in a mixed spin-($1$,$1/2$,$1$) Heisenberg trimer, accounting for different exchange coupling constants between identical and distinct spins. Bipartite negativities between the single-spin entity and the remaining spin dimer are analyzed alongside the global tripartite negativity (gTN) of the whole trimer under the effect of an external magnetic field and both easy-axis and easy-plane types of single-ion anisotropy. Interestingly, the single-ion anisotropy significantly influences the degree of entanglement by altering the stability regions of energetically preferred ground states and it may also introduce additional phases in the overall ground-state phase diagram. Moreover, it is demonstrated that within specific ground states, the degree of entanglement primarily depends on the strength of single-ion anisotropy, altering the respective probability amplitudes of the corresponding eigenvectors. Finally, the thermal stability of entanglement is discussed in detail, including the emergence of a peculiar local minimum at finite temperatures. The obtained theoretical results may offer deeper insights into bipartite and tripartite entanglement in trimetallic Ni$^{2+}$-Cu$^{2+}$-Ni$^{2+}$ molecular compounds.
title Effect of Single-Ion Anisotropy on Stability of Quantum and Thermal Entanglement in a Mixed-Spin Heisenberg Trimer
topic Quantum Physics
url https://arxiv.org/abs/2509.01451