  We present a theoretical analysis of the role that strain plays on the
electronic structure of chromium nitride crystals. We use LSDA+U calculations
to study the elastic constants, deforma- tion potentials and strain dependence
of electron and hole masses near the fundamental gap. We consider the lowest
energy antiferromagnetic models believed to describe CrN at low temperatures,
and apply strain along different directions. We find relatively large
deformation potentials for all models, and find increasing gaps for tensile
strain along most directions. Most interestingly, we find that compressive
strains should be able to close the relatively small indirect gap (' 100 meV)
at moderate amplitudes ' 1.3%. We also find large and anisotropic changes in
the effective masses with strain, with principal axes closely related to the
magnetic ordering of neighboring layers in the antiferromagnet. It would be
interesting to consider the role that these effects may have on typical film
growth on different substrates, and the possibility of monitoring optical and
transport properties of thin films as strain is applied.
