Nonlinear magnetodielectric effect in double-perovskite Gd₂NiMnO₆

Magnetic and dielectric properties of the double perovskite Gd₂NiMnO₆ were investigated. Ferromagnetic order of alternating Ni²⁺ and Mn⁴⁺ spins arises below K and an additional order of Gd³⁺ spins occurs at K. The formation of short-range ferromagnetic clusters accompanied by a Griffiths phase-like feature below K is also suggested. Under the low enough dielectric loss at low temperature regime excluding the influence of the extrinsic effect, a highly nonlinear variation of the dielectric constant was achieved in application of the magnetic fields. Our finding offers an efficient approach to accomplish intrinsically coupled functionality utilizing both magnetic and dielectric quantities.