Bipartite entanglement in the spin-1/2 Ising-Heisenberg planar lattice constituted of identical trigonal bipyramidal plaquettes

TL;DR

This paper investigates bipartite entanglement in a spin-1/2 Ising-Heisenberg planar lattice with bipyramidal plaquettes, revealing how entanglement varies with temperature and ground state degeneracy.

Contribution

It provides a rigorous analysis of entanglement behavior in a complex lattice model, highlighting differences between chiral and non-chiral entanglement at various temperatures.

Findings

Heisenberg spins are twice as entangled in the degenerate ground state compared to the chiral state.

Entanglement with chiral features disappears at or below the critical temperature.

Non-chiral entanglement can persist above the critical temperature, showing non-monotonous temperature dependence.

Abstract

The bipartite entanglement is rigorously examined in the spin-$1/2$ Ising-Heisenberg planar lattice composed of identical inter-connected bipyramidal plaquettes at zero and finite temperatures using the quantity called concurrence. It is shown that the Heisenberg spins of the same plaquette are twice stronger entangled in the two-fold degenerate quantum ground state than in the macroscopically degenerate quantum chiral one. The bipartite entanglement with chiral features completely disappears below or exactly at the critical temperature of the model, while that with no chirality may survive even above the critical temperature of the model. Non-monotonous temperature variations of the concurrence clearly evidence the activation of the entangled Heisenberg states also above classical ground state as well as their re-appearance above the critical temperature of the model.