  In this paper, the structural, electronic and magnetic properties of
Zinc-blende Ga1-xVxSb compounds, with x from dilute doping situation to extreme
doping limiting, were systematically investigated by first-principles
calculations. V atoms prefer to substitute the Ga atoms and the formation
energy is lower in Sb-rich than Ga-rich growth condition. Meantime, the SbGa
antisite defects can effectively decrease the energy barrier of substitution
process, from 0.85 eV to 0.53 eV. The diffusion of V atom in GaSb lattice is
through meta-stable interstitial sites with an energy barrier of 0.6 eV. At a
low V concentration x = 0.0625, V atoms prefer a homogeneous distribution and
an antiferromagnetic coupling among them. However, starting from x = 0.5, the
magnetic coupling among V atoms changes to be ferromagnetic, due to enhanced
superexchange interaction between eg and t2g states of neighbouring V atoms. At
the extreme limiting of x = 1.00, we found that Zinc-blende VSb as well as its
analogs VAs and VP are intrinsic ferromagneitc semiconductors, with a large
change of light absorption at the curie temperature. These results indicate
that Ga1-xVxSb compounds can provide a platform to design the new electronic,
spintronic and optoelectronic devices.
