Intersublattice entanglement entropy of ferrimagnetic spin chains

TL;DR

This paper analytically derives the intersublattice entanglement entropy of ferrimagnetic spin chains with arbitrary spins, revealing its dependence on spin difference and stability against parameter variations, verified by numerical methods.

Contribution

It provides the first analytical expression for ferrimagnet entanglement entropy with arbitrary spins, extending previous antiferromagnetic results.

Findings

Entanglement entropy depends on the difference of spins relative to their geometric average.

Analytical results are numerically verified using density matrix renormalization group.

Entanglement entropy remains stable against small parameter variations.

Abstract

Ferrimagnets are antiparallel-ordered magnetic states in a bipartite lattice with two alternating unequal spins, which exhibit both ferromagnetic and antiferromagnetic properties. Several theoretical studies have explored the magnetic properties of ferrimagnets, but the entanglement entropy of ferrimagnets with arbitrary spin combinations has not been studied. In this study, we analytically derive the intersublattice entanglement entropy of a ferrimagnetic spin chain using the method that has been applied to the antiferromagnetic case. The analytical results are numerically verified using the density matrix renormalization group. Going beyond the results for antiferromagnets, the entanglement entropy of ferrimagnets for fixed anisotropy is shown to solely depend on the difference of spins relative to its geometric average, and the quantity is shown to be stable against small parameter variations.