# Thermal entanglement in a spin-1/2 Ising-XYZ distorted diamond chain with the second-neighbor interaction between nodal Ising spins

## TL;DR

This paper analyzes the thermal entanglement properties in a complex spin-1/2 Ising-XYZ distorted diamond chain, revealing phases influenced by anisotropy and second-neighbor interactions, and explores how entanglement varies with temperature and magnetic field.

## Contribution

It provides an exact solution for the model and investigates the behavior of quantum entanglement, including reentrant phenomena, in relation to temperature and magnetic field effects.

## Key findings

- Concurrence shows both standard and reentrant thermal dependence.
- Entanglement persists up to approximately 30 K in azurite.
- Model exhibits multiple phases due to anisotropy and second-neighbor interactions.

## Abstract

We consider a spin-1/2 Ising-XYZ distorted diamond chain with the XYZ interaction between the interstitial Heisenberg dimers, the nearest-neighbor Ising coupling between the nodal and interstitial spins, respectively, and the second-neighbor Ising coupling between the nodal spins. The ground-state phase diagram of the spin-1/2 Ising-XYZ distorted diamond chain exhibits several intriguing phases due to the XY anisotropy and the second-neighbor interaction, whereas the model can be exactly solved using the transfer-matrix technique. The quantum entanglement within the Heisenberg spin dimers is studied through a bipartite measure concurrence, which is calculated from a relevant reduced density operator. The concurrence may either show a standard thermal dependence with a monotonous decline with increasing temperature or a more peculiar thermal dependence accompanied with reentrant behavior of the concurrence. It is conjectured that the bipartite entanglement between the interstitial Heisenberg spin pairs in the natural mineral azurite is quite insensitive to the applied magnetic field and it persists up to approximately 30 Kelvins.