First Principles Study of Electronic and Magnetic Properties of DyNiPb and YNiPb Compounds Under Hydrostatic Pressure

Density functional theory calculations have been performed to study the electronic and magnetic properties of DyNiPb and YNiPb compounds. The total energy calculations indicate that at zero pressure the ferromagnetic and nonmagnetic phases are the most stable phases of the DyNiPb and YNiPb compounds respectively. The Pb atom has a negligible contribution to the magnetic properties of DyNiPb compared to the Dy and Ni atoms. The effect of hydrostatic pressure on the magnetic moment of these compounds is also studied. The calculated results show that the YNiPb compound has zero magnetic moment over the whole pressure range considered (p < 20 GPa), while in the DyNiPb compound the total and local magnetic moments at the Dy and Ni atomic sites increase with increasing pressure. Furthermore, I have investigated the electric field gradient (EFG) at different atomic sites of these compounds. The contribution of different orbitals to the EFG shows that the strongest anisotropy in the charge distribution is due to the electrons in the p orbitals. The variation of EFG at different atomic positions of the DyNiPb and YNiPb compounds with pressure is not linear and increases with pressure.