First-principles predictions of low-energy phases of multiferroic BiFeO₃

We used first-principles methods to perform a systematic search for potentially stable phases of multiferroic BiFeO₃. We considered a simulation cell compatible with the atomic distortions that are most common among perovskite oxides and found a large number of local minima of the energy within 100 meV/f.u. of the ferroelectric ground state. We discuss the variety of low-symmetry structures discovered, as well as the implications of these findings as regards current experimental (e.g., on thin films displaying supertetragonal phases) and theoretical (on models for BiFeO₃'s structural phase transitions) work on this compound.