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 Cu 2+ and Sm 3+ -ions moments at T N1 = 23 K and T N2 = 5 K, respectively. Applied magnetic field induces dielectric anomaly at T N1 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 N2 shows a small (0.4%) magnetocapacitance effect. Interestingly, applied magnetic field induces an electric polarization below T N1 and the polarization 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 N2 , the electric polarization decreases from 35 to 29 µC/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.

Magnetic-field-induced ferroelectric states in centrosymmetric R2BaCuO5 ( R=Dy and Ho)

“…3(e) and 3(f). The calculated magnetoelectric coefficient α of Dy 2 BaCuO 5 is 3.47 ps/m (1 T and 10 K) and 7.37 ps/m (2.5 T and 2 K), which is higher than that of the isostructural compound Sm 2 BaCuO 5 [38].…”

“…The corresponding electric polarization is shown in Fig. 3(d [38]. With increasing magnetic field, electric polarization increases linearly up to metamagnetic transition, as shown in Fig.…”

“…The R 2 BaCuO 5 family of compounds, where R = Sm-Lu and Y, so-called green phases, exhibit various magnetic structures depending on the R ion due to 4 f -3d exchange interaction and R ion magnetic anisotropy [4,[30][31][32][33][34][35][36][37][38]. The ground state magnetic structures possess different propagation vectors for each compound, for example, k C = (0, 0, 0) for R = Sm, Dy; k C1 = (0, 1 2 , 0) + k C2 = (0, 0, 0) for Ho;…”

“…, 0) for R = Er and Tm; and k C = (0, 0, 1 2 ) for R = Gd [4,[38][39][40][41]. In the viewpoint of magnetic symmetry analysis, these compounds might be promising candidates to exhibit either magnetoelectric or multiferroic properties [42].…”

“…In the viewpoint of magnetic symmetry analysis, these compounds might be promising candidates to exhibit either magnetoelectric or multiferroic properties [42]. Recently, a linear magnetoelectric effect has been reported below T Cu N = 23 K in Sm 2 BaCuO 5 [38]. Below the independent ordering of Sm (T Sm N = 5 K), the electric polarization decreases.…”