Epitaxial-strain-induced multiferroicity in SrMnO3 from first principles.

First-principles calculations reveal a large spin-phonon coupling in cubic SrMnO3, with ferromagnetic ordering producing a polar instability. Through combination of this coupling with the strain-polarization coupling characteristic of perovskites, the bulk antiferromagnetic-paraelectric ground state is driven to a previously unreported multiferroic ferroelectric-ferromagnetic state by increasing epitaxial strain. This state has a computed P(s)>54  μC/cm2 and magnetic T(c)>92  K. Large mixed magnetic-electric-elastic responses are predicted in the vicinity of the phase boundaries.