The Magnetic Field In The Antiferromagnetic Model The Thermal Entanglement

We investigate the thermal entanglement in A-type antiferromagntetic modelunder a magnetic field. In this article, we firstly study the thermal entanglement inA-type antiferromagnetic model, and obtain an analytical expression for the concur-rence C of this system in terms of the intra-layer coupling constant J_ab, inter-layercoupling constant J_c and temperature T. C reduces with the temperature increasing,and increases with the increasing of coupling constants. The critical temperature T_cis improved with the increasing of coupling constants. The result also shows the J_abhas a better action on improving thermal entanglement than J_c. We also study thethermal entanglement in A-type antiferromagnetic model under an magnetic field,homogeneous magnetic and inhomogeneous magnetic, respectively. In homogeneousmagnetic, we have found that the concurrence is decreasing with the increasing oftemperature T and magnetic B. In lower temperature, the concurrence drops moreabruptly with B. We can control coupling constants and magnetic to improve entan-glement. In inhomogeneous magnetic, C reduces with the increasing inhomogeneousmagnetic b. The critical magnetic field B_c increases with the increasing of b, butthe maximum entanglement value of the system will become smaller than 1. Thecritical inhomogeneous magnetic field b_c is independent of J_c.