Linear magnetoelectric effect in antiferromagnetic Sm2BaCuO5

Abstract

We report the discovery of linear magnetoelectric effect in the well-known green-phase compound, Sm 2 BaCuO 5 , which crystallizes in the centrosymmetric orthorhombic (Pnma) structure. Magnetization and specific heat measurements reveal the long-range antiferromagnetic ordering of C u 2 + − and Sm 3 + ions moments at T N 1 = 23 K and T N 2 = 5 K , respectively. Applied magnetic field induces dielectric anomaly at T N 1 whose magnitude increases with field, which results in significant (1.7%) magnetocapacitance effect. On the other hand, the dielectric anomaly observed in zero-applied magnetic field at T N 2 shows a small (0.4%) magnetocapacitance effect. Interestingly, applied magnetic field induces an electric polarizaiton, below T N 1 , that varies linearly up to the maximum applied field of 9 T with the magnetoelectric coefficient α ∼ 4.4 ps/m, demonstrating high magnetoelectric coupling. Below T N 2 , the electric polarization decreases from 35 to 29 μ C / m 2 at 2 K and 9 T due to ordering of Sm sublattice. The observed linear magnetoelectricity in Sm 2 BaCuO 5 is explained using symmetry analysis.