Thermal Entanglement of a Spin-1/2 Ising-Heisenberg Model on a Symmetrical Diamond Chain

TL;DR

This paper provides an exact analysis of thermal entanglement in a spin-1/2 Ising-Heisenberg model on a symmetrical diamond chain, revealing novel entanglement behaviors influenced by magnetic field and interactions.

Contribution

It introduces exact analytical expressions for bipartite entanglement in the model, considering external fields and interactions, and uncovers new entanglement phenomena.

Findings

Exact formulas for concurrence were derived.

Two-peak behavior of concurrence versus temperature was observed.

Coexistence of phases with different magnetic entanglement was identified.

Abstract

The entanglement quantum properties of a spin-1/2 Ising-Heisenberg model on a symmetrical diamond chain were analyzed. Due to the separable nature of the Ising-type exchange interactions between neighboring Heisenberg dimers, calculation of the entanglement can be performed exactly for each individual dimer. Pairwise thermal entanglement was studied in terms of the isotropic Ising-Heisenberg model, and analytical expressions for the concurrence (as a measure of bipartite entanglement) were obtained. The effects of external magnetic field $H$ and next-nearest neighbor interaction $J_m$ between nodal Ising sites were considered. The ground-state structure and entanglement properties of the system were studied in a wide range of the coupling constant values. Various regimes with different values of the ground-state entanglement were revealed, depending on the relation between competing interaction strengths. Finally, some novel effects, such as the two-peak behavior of concurrence versus temperature and coexistence of phases with different values of magnetic entanglement were observed.