Magnetodielectric effects in low-dimensional cobalt oxides

We have investigated the magnetic and dielectric properties of BaCo 2 Si 2 O 7 single crystal with a quasi-one-dimensional structure to explore novel magnetoelectric functionality. The Weiss temperatures estimated in paramagnetic region are - 20 K ( H ∥ c ) and - 74 K ( H ⊥ c ) , indicating the large magnetic anisotropy due to the highly anisotropic structure. The weak ferromagnetic magnetization rises up at 21 K, where the dielectric constant perpendicular to the c-axis decreases concomitantly. In addition, we have observed the magnetocapacitance effect below 21 K. Δ e ( H ) / e ( 0 ) reaches 0.2% at 5.5 K. These results suggest that there exists a substantial coupling between magnetism and dielectricity.