Magnetoelectric property in 3d transition metal oxide with tetrahedral structure

Abstract

We have investigated anisotropic properties of magnetism and dielectricity in CaBaCo4O7 single crystal, which has layered structure consisting of CoO4 tetrahedra. The crystallographic symmetry of CaBaCo4O7 is Pbn21 at room temperature, which breaks the inversion symmetry. The magnetic moments along the a- and b-axes rise at 64 K, suggesting a weak ferromagnetism. We have also observed an increase of electric polarization and a peak of dielectric constant along the b- and c-axes at the magnetic transition temperature. In addition, the large magnetocapacitance effect was observed near above the transition temperature: Δ∊c(Hb)/∊c(0) ≡ [∊c(Hb) - ∊c(0)]/∊c(0) reaches over 50 % at 68 K.