  Thermal entanglement of a two-qubit Ising chain subjected to an external
magnetic field and Dzialoshinski-Moriya (DM) interaction is examined. The
effect of magnetic field, strength of DM interaction and temperature are
analyzed by adopting negativity of partial transpose as the measure of
entanglement. It is shown that when the DM interaction along the Ising axis is
considerable, thermal entanglement can be sustained for higher temperature. The
usefulness of longitudinal DM interaction over the one that is perpendicular to
the Ising axis, in the manipulation and control of entanglement at a feasible
temperature, is illustrated.
