First-principles study of a pressure-induced spin transition in multiferroic Bi2FeCrO6

We report on a first-principles study of the structural, electronic, and magnetic properties of multiferroic double perovskite Bi2FeCrO6, using density functional theory within the local spin-density approximation (LSDA), the LSDA + U approximation as well as a hybrid functional scheme. We show that Bi2FeCrO6 presents two competing ferrimagnetic phases, sharing the same total magnetic moment of 2 mu(B) per unit cell but with a different electronic configuration for the Fe3+ species. The phase with high-spin iron is the ground state at ambient conditions, but we predict that low-spin iron gets stabilized under compression. We also investigate the corresponding ferromagnetic phases, and show that the magnetic couplings sharply decrease when moving form high- to low-spin Fe3+.