  First principles studies were performed in order to find out the possibility
of inducing half-metallicity in Heusler Compound CoFeMnSb, by means of alloying
it with 3d-transition metal elements. Proper alloying element is selected
through the calculations of formation energies. These calculations were tested
with different concentrations of alloying elements at different atomic sites.
Among the selected transition metal elements Sc and Ti are proposed to be
excellent alloying elements particularly at Mn site. By using these alloying
elements complete half metallic behaviour is obtained in CoFeMn0.25Sc0.75Sb,
CoFeMn0.75Ti0.25Sb, CoFeMn0.625Ti0.375Sb, CoFeMn0.50Ti0.50Sb,
CoFeMn0.25Ti0.75Sb and CoFeTiSb alloys. Shifting of Co-Fe d-states towards
lower energy region leads to zero density of states at Fermi level for the spin
minority channel. Alloying effects on the electronic structure and
magnetization are discussed in details. Thermodynamical stability of these new
alloys are major part of this study. The Curie temperatures of
CoFeMn0.25Sc0.75Sb and CoFeMn0.75Ti0.25Sb were found to be 324.5 K and 682 K;
respectively, showing good candidature for spintronics applications. For
understanding the bonding nature of constituent atom of CoFeMnSb, crystal
orbital Hamiltonian populations have been analysed.
