  New materials are currently sought for use in spintronics applications.
Ferromagnetic materials with half metallic properties are valuable in this
respect. Here we present the electronic structure and magnetic properties of
binary compounds consisting of 3d transition metals and group V elements viz.
P, Sb and As in the zinc-blende structure. We demonstrate that compounds of V,
Cr and Mn show half metallic behavior for appropriate lattice constants.
  By comparing the total energies in the ferromagnetic and antiferromagnetic
structures, we have ascertained that the ferromagnetic phase is stable over the
antiferromagnetic one. Of the different compounds studied, the Cr based systems
exhibit the strongest interatomic exchange interactions, and are hence
predicted to have the highest critical temperatures. Also, we predict that VAs
under certain growth conditions should be a semiconducting ferromagnet.
Moreover, critical temperatures of selected half metallic compounds have been
estimated from mean field theory and Monte Carlo simulations using parameters
obtained from a {\it ab-initio} non-collinear, tight binding linearized
muffin-tin orbital method. From a simple model, we calculate the reflectance
from an ideal MnAs/InAs interface considering the band structures of MnAs and
InAs. Finally we present results on the relative stabilities of MnAs and CrSb
compounds in the NiAs and zinc-blende structures, and suggest a parameter space
in substrate lattice spacings for when the zinc-blende structure is expected to
be stable.
