Spin rotation driven ferroelectric polarization with a 180°flop in double-perovskite Lu₂CoMnO₆

Structure-property relationships are a key outstanding problem in the study of magnetoelectric multiferroic materials. First-principles calculations were used to explore the influences of Hubbard-U on the ground state of double-perovskite Lu₂CoMnO₆ as determined by band gap, magnetic moment, spontaneous polarization and structural parameters. The origin of ferroelectricity in the multiferroic Lu₂CoMnO₆ is elucidated by the calculations of collinear and non-collinear magnetic structure. It is confirmed that the up-up-down-down spin arrangement plays a significant role in the ferroelectric (FE) polarization by the contrast of the lattice geometries and electronic structures in different magnetic orders. The current study shows that both the mechanisms of exchange strictive effects and spin-charge ordering are simultaneously active and lead to the ferroelectric polarization in Lu₂CoMnO₆. Similar to the early discoveries in HoMnO₃ and DyFeO₃, we also found and explained the mechanism of switching the ferroelectric polarization via a 180°coherent rotation of Co and Mn spins in double-perovskite Lu₂CoMnO₆.