Quantum entanglement in the neighborhood of pseudo-transition for a spin-1/2 Ising-XYZ diamond chain

• Published in: Journal of magnetism and magnetic materials 2018-11, Vol.465, p.323-327
• Main Authors: Carvalho, I.M., Torrico, J., de Souza, S.M., Rojas, M., Rojas, O.
• Format: Article
• Language: English
• Subjects: Chains; Critical temperature; Diamonds; Entropy; Ising model; Magnetic fields; One dimensional models; Particle spin; Phase transitions; Phases; Quantum entanglement; Quantum mechanics; Quantum physics; Temperature; Transition temperature
• ISSN: 0304-8853; 1873-4766
• DOI: 10.1016/j.jmmm.2018.06.018

•The model presents interesting properties in quasi-phase region.•At finite temperature it is possible to define the spin orientations.•The entropy remains almost zero with increasing the temperature. Recently has been observed for some one-dimensional models that exhibit unexpected pseudo-transitions and quasi-phases. This pseudo-transition resembles a first- and second-order phase transition simultaneously. One of those models is the spin-1/2 Ising-XYZ diamond chain, composed of Ising spin particles at the nodal sites and the Heisenberg spin particles at the interstitial sites. Where we assume Ising-type interaction between the nodal and interstitial sites, the Heisenberg-type interaction between interstitial sites, and with an external magnetic field applied along the z-axis. This model presents an exact analytical solution applying the transfer matrix technique, which shows 3 phases at zero temperature in the vicinity of pseudo-transition. The pseudo-transition separates quasi-phases, these quasi-phases still hold at a finite temperature most of the pattern configurations of a true phase at zero temperature. Here we study the quantum entanglement of pair spin particles in the quasi-phase regions, which can be measured through the concurrence. Then we observe an unexpected behavior in the concurrence, that is below pseudo-critical temperature the concurrence remains almost constant up to pseudo-critical temperature, but above the pseudo-critical temperature, the concurrence behaves as for the standard one-dimensional spin models. Further, we consider the entropy behavior of the system, below pseudo-critical temperature the entropy becomes almost null, while above pseudo-critical temperature the system exhibits standard behavior as for ordinary one-dimensional spin models.