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Thermal quantum discord in the anisotropic Heisenberg XXZ model with the Dzyaloshinskii-Moriya interaction

The thermal quantum discord (QD) is studied in a two-qubit Heisenberg XXZ system with Dzyaloshinskii-Moriya (DM) interaction. We compare the thermal QD with thermal entanglement in this system and find remarkable differences between them. For instance, we show situations where QD decreases asymptotically to zero with temperature $T$ while entanglement decreases to zero at the point of critical temperature, situations where QD decreases with certain tunable parameters such as $D_z$ and $D_x$ when entanglement increases. We find that the characteristic of QD is exotic in this system and this possibly offers a potential solution to enhance entanglement of a system. We also show that tunable parameter $D_x$ is more efficient than parameter $D_z$ in most regions for controlling the QD.