Electronic and magnetic properties of CdI2-type MX2 (M = V, Nb; X = Al, Ga and In) compounds

First-principle calculations within the density-functional theory is used to investigate the possibility of existence of ferromagnetism in hypothetical CdI2-type MX2 (M = V, Nb; X = Al, Ga and In) compounds. The TBLMTO-ASA program is used for this purpose. Both spin-polarization and non-spin-polarization calculations are carried out for each compound. The spin-polarization calculation shows that VX2 (X = Al, Ga and In) compounds are ferromagnets whereas NbX2 (X = Al, Ga and In) compounds are non-magnets because no effective polarization of the energy states occurs at their equilibrium volume. However, the NbX2 (X = Al, Ga and In) compounds become ferromagnets under large volume expansion. Ferromagnetism in these compounds is predicted for the first time. The variation of lattice constant with magnetic moment for VX2 (X = Al, Ga and In) compounds are also analysed. The magnetism arises mainly from the cation d-like states. This result is similar to other transition-metal based pnictide and chalcogenide compounds. The ground-state properties like equilibrium lattice parameters, bulk modulus, heat of formation and total and partial magnetic moments are calculated.