Sc2NiMnO6: A Double-Perovskite with a Magnetodielectric Response Driven by Multiple Magnetic Orders

Perovskite materials provide a large variety of interesting physical properties and applications. Here, we report on unique properties of a fully ordered magnetodielectric double-perovskite, Sc2NiMnO6 (space group P21/n, a = 4.99860 Å, b = 5.35281 Å, c = 7.34496 Å, and β = 90.7915°), exhibiting sequential magnetic transitions at T 1 = 35 K and T 2 = 17 K. The transition at T 1 corresponds to a single-k antiferromagnetic phase with propagation vector k 1 = (1/2, 0, 1/2), while the second transition at T 2 corresponds to a 2-k magnetic structure with propagation vectors k 1 = (1/2, 0, 1/2) and k 2 = (0, 1/2, 1/2). Symmetry analysis suggests that the two ordering wave vectors are independent, and calculations imply that k 1 is associated with the Mn sublattice and k 2 with the Ni sublattice, suggesting that Mn–Ni coupling is very small or absent. A magnetodielectric anomaly at T 2 likely arises from an antiferroelectric ordering that results from the exchange-striction between the two magnetic sublattices belonging to k 1 and k 2 . The behavior of Sc2NiMnO6 demonstrates 3d double-perovskites with small A-site cations as a promising avenue in which to search for magnetoelectric materials.