Thermal Entanglement in the Pure Dzyaloshinskii-Moriya Model with Magnetic Field**Supported by the National Natural Science Foundation of China under Grant Nos 11204061, 11374085, 11274010 and 11204002, the Anhui Provincial Natural Science Foundation under Grant No 1408085MA16, the China Postdoctoral Science Foundation under Grant No 20110490825, the Key Project of the Ministry of Education of China under Grant No 211080, the

Abstract

We investigate the effects of the directions of Dzyaloshinskii-Moriya (DM) interaction and magnetic field on the thermal entanglement in the pure DM model. It is found that when the Hamiltonian is H1 = D · (σ1 ⊗ σ2)+ B · σ1, the entanglement can reach its maximum if the directions of the magnetic field and the DM vector are parallel. In addition, when the Hamiltonian is H2 = D · (σ1 ⊗ σ2) + B · (σ1 + σ2), if the directions of the magnetic field and the DM vector are perpendicular in a high magnetic field, or their directions are parallel in a weak magnetic field, the entanglement can also reach its maximum. Thus the entanglement can be enhanced by adjusting the direction of the external magnetic field, and this is feasible within the current experimental technology.