The multiferroic phase of DyFeO(3): an ab initio study

GENERAL SCIENTIFIC SUMMARY Introduction and background. Multiferroics are materials where ferroelectricity and magnetism coexist in the same compound. They offer a promising route to create multifunctional devices where the charges can be controlled by an applied magnetic field and spins can be manipulated by an applied voltage. They also constitute an interesting class of materials due to their astoundingly rich playground for fundamental condensed-matter physics. In these materials, a noncentrosymmetric spin, charge or orbital order breaks inversion symmetry and can give rise to a permanent electric dipolar order. Main results. We study DyFeO3, a perovskite compound where the electric dipoles arise due to a subtle interaction between Dy 4f and the Fe 3d states mediated by oxygens. Our calculations show that the spin ordering of Dy atoms is crucial in order to stabilize the ferroelectricity, confirming previous experimental results. Wider implications. Our study elucidates the microscopic origin of the ferroelectricity in DyFeO3, showing that 4f electrons, often neglected in the theoretical calculations, are crucial for the onset of ferroelectric order, and they can serve as an additional degree-of-freedom for tailoring multiferroic properties.