Investigation of Co2MnX (X=Al, Ga, Ge, Si) heusler alloys, in cubic form, in terms of their structural, electronic, elastic and vibrational properties using density functional theory

In this thesis, the structural, electronic, elastic and vibrational properties of the Co2MnX (X=Al, Ga, Ge, Si) Heusler alloys in L21 structure have been investigated using first principles, namely density functional theory (DFT) with the Generalized Gradient Approximation (GGA) method. The ground state properties, like lattice constant, bulk modulus and its first derivative obtained from our calculations agree well with experimental and other theoretical calculations. We predict the ferromagnetic phases of the alloys Co2MnGe and Co2MnSi to be half metals. The electronic band structures these materials are also presented. The calculated total spin magnetic moments are 4,06 µB for Co2MnAl, 4,16 µB for Co2MnGa, 5,01 µB for Co2MnGe and 5,00 µB for Co2MnSi, which agree well with the previous theoretical calculations. Phonon dispersion curves, total and partial density of states were calculated by employing a density functional perturbation theory. The results are compared with previous calculations for Co2MnGa and Co2MnGe along the ?-X symmetry directions.