We report the discovery of linear magnetoelectric effect in the well-known green-phase compound, ${\mathrm{Sm}}_2{\mathrm{BaCuO}}_5$, which crystallizes in the centrosymmetric orthorhombic (Pnma) structure. Magnetization and specific heat measurements reveal the long-range antiferromagnetic ordering of $\mathrm{C}{\mathrm{u}}^{2+}-$ and ${\mathrm{Sm}}^{3+}$ ions moments at $T_{\mathrm{N}1}=23\mathrm{K}$ and $T_{\mathrm{N}2}=5\mathrm{K}$, respectively. Applied magnetic field induces dielectric anomaly at $T_{\mathrm{N}1}$ 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 $T_{\mathrm{N}2}$ shows a small (0.4%) magnetocapacitance effect. Interestingly, applied magnetic field induces an electric polarizaiton, below $T_{\mathrm{N}1}$, 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 $T_{\mathrm{N}2}$, the electric polarization decreases from 35 to $29\mu \mathrm{C}/{\mathrm{m}}^2$ at 2 K and 9 T due to ordering of Sm sublattice. The observed linear magnetoelectricity in ${\mathrm{Sm}}_2{\mathrm{BaCuO}}_5$ is explained using symmetry analysis.

• Received 15 April 2019
• Revised 9 July 2019

DOI:https://doi.org/10.1103/PhysRevB.100.104417