Abstract
In order to explore the effect of external temperature T in quantum correlation we compute thermal entanglement and thermal discord analytically in the Heisenberg X Y Z model with Dzyaloshinskii-Moriya Interaction term D · ( σ₁ × σ₂ ). For the case of thermal entanglement it is shown that quantum phase transition occurs at T = T_c due to sudden death phenomenon. For antiferromagnetic case the critical temperature T_c increases with increasing |D|. For ferromagnetic case, however, T_c exhibits different behavior in the regions |D| ≥ |D_*| and |D| < |D_*|, where D_* is particular value of D. It is shown that T_c becomes zero at |D| = |D_*|. We explore the behavior of thermal discord in detail at T ≈ T_c. For antiferromagnetic case the external temperature makes the thermal discord exhibit exponential damping behavior, but it never reaches to exact zero. For ferromagnetic case the thermal entanglement and thermal discord are shown to be zero simultaneously at T_c = 0 and |D| = |D_*|. This is unique condition for simultaneous disappearance of thermal entanglement and thermal discord in this model.