Pressure dependence of exchange interactions in NiO

We investigate systematically the magnetic exchange interactions and related properties of NiO under high pressure based on first-principles calculations. Accurate magnetic exchange parameters are obtained using GGA+U. The pressure dependence of the superexchange constants are found to be in excellent agreement with experiment. Present results also give a theoretical evidence that the Bloch's law is valid under high pressure in the case of NiO. In addition, the Neel temperature and the rhombohedral distortion under high pressure are evaluated. These results are consistent with experiments and the related mechanisms are also discussed