Effect of Pressure on the Electronic and Magnetic Properties of a Few Mn-Based Half-Metallic Compounds

Spin-polarized calculations of three half-metallic, half-Heusler compounds, namely NiMnSb, PdMnSb and PtMnSb are presented. The calculations were performed using tight-binding linear muffin-tin orbital method within the local density approximation. In this work, the lattice constants, bulk modulus, band structures, density of states and energy gap in the minority spin direction and magnetic moment of these compounds were calculated at ambient conditions and under pressure. The effect of pressure on the magnetic properties and on the energy gap was studied. We have predicted that NiMnSb, PdMnSb and PtMnSb show the magnetic phase transition under pressure from the ferromagnetic to nonmagnetic phase at 195.6, 292.4 and 533 GPa, respectively. The magnetic phase transition is of second order in nature. The transition pressure increases from Ni(3 d ) to Pt(5 d ) in the compound. The calculated energy gap in the minority spin direction increases with pressure. The bulk modulus of these compounds have been predicted to be 140.2, 137.25 and 157.45 GPa, respectively.