The effect of an external magnetic field on permittivity has been studied in a Cu3B2O6 single crystal
with a layered structure in the direction perpendicular to layers (bc-planes). It has been found that the appreciable
magnetodielectric effect in the temperature range below the Néel temperature (≈10 K) takes place only
at one magnetic field orientation H and one crystallographic direction, i.e., H . b. Such “selectivity” of the
magnetodielectric effect correlates with the anisotropic behavior of magnetic properties of the crystal.