Thermal entanglement in a two-qubit Heisenberg XY chain with the Dzyaloshinskii--Moriya interaction

This paper investigates thermal entanglements of a two-qubit Heisenberg XY chain in the presence of the Dzyaloshinskii--Moriya anisotropic antisymmetric interaction. By the concept of concurrence, it is found that the effects of spin--orbit coupling on the entanglement are different from those of spin--spin model. The analytical expressions of concurrence are obtained for this model.