Magnetodielectric effect from the onset of ferrimagnetic transition in CoCr2O4

Multiferroicity in CoCr2O4 is generally regarded to emerge from the onset of noncollinear spiral magnetic order (T-s approximate to 28 K) due to the inverse Dzyaloshinskii-Moriya interaction, far below the temperature of collinear ferrimagnetic transition (T-c approximate to 96 K). So far, the possibility of multiferroicity appearing in collinear magnetic order has been rarely explored. Here, we report a magnetodielectric effect emerging from the onset of collinear ferrimagnetic transition T-c in CoCr2O4. Based on the postulation of non-centric crystal symmetry and Landau theory, we deduce that such a magnetodielectric effect is attributed to the coexistence of electric and magnetic ordering by the magnetoelectric coupling below T-c. Our results suggest that CoCr2O4 is a natural multiferroic in both noncollinear spiral and collinear magnetic ordering.