  Epitaxial strain has been shown to drive structural phase transitions along
with novel functionalities in perovskite-based thin-films. Aliovalent doping at
the A-site can drive an insulator-to-metal and magnetic transitions in
perovskites along with a variety of interesting structural and electronic
phenomena. Using first-principles calculations, we demonstrate here, how
coupling epitaxial strain with A-site hole doping in a multiferroic double
perovskite, Bi2FeCrO6, could lead to mitigation of issues related to anti-site
defects and lowered magnetisation in thin-films of the material. We also show
that epitaxial strain can be used to manipulate the hole states created by
doping to induce half-metal to insulator, antipolar to polar, antiferromagnetic
to ferromagnetic, orbital ordering and charge ordering transitions. We also
predict the formation of a half-metallic polar phase with a large magnetic
moment which could be of immense fundamental and technological significance.
