Thermal entanglement of the mixed spin-1/2 and spin-5/2 Heisenberg model under an external magnetic field

We use the concept of negativity to study the entanglement of spin-1/2 and spin-5/2 antiferromagnetic Heisenberg model with an inhomogeneous magnetic field. Analytical conclusions of the model are acquired. It is found that the critical temperature T-c goes up, as the increase of anisotropy parameter k. The temperature T-c becomes bigger than the results of spin-1/2 and spin-3/2 Heisenberg XXZ chain for the same value of k. And we can gain more entanglement at higher temperature by coordinating the value of inhomogeneity b.