Structure driven magnetic correlations and magnetodielectric coupling in 6H-perovskite Ba3DyRu2O9

Abstract

The 6H-perovskites Ba3(R/M)Ru2O9 (R = rare Earth, M = transition metal) exhibit complex magnetism and have been extensively studied recently for their magnetodielectric (MD) properties. Here, we present a detailed study of structural, magnetic, thermodynamic and MD properties of a 6H-perovskite Ba3DyRu2O9. This compound is found to undergo long range antiferromagnetic ordering below ∼5.8 K (T N), along with the presence of metamagnetic transition at low temperatures. The heat capacity shows two additional anomalies at ∼28 K (T 1) and ∼33 K (T 2), besides the anomaly at T N. Signature of these anomalies is also visible in the derivative of magnetization curve. The dielectric response also shows weak anomalies around T 1 and T 2 at zero field whereas anomaly at T 2 gets suppressed at 80 kOe. The observed MD coupling of ∼2%–4% at 80 kOe field below ∼30 K temperature range, is among the highest values observed for the compounds of this family. Low temperature crystal structures of the compound show sharp distortion of Ru2O9 octahedra near T 2. Our study points toward the emergence of structurally driven spin correlations of Ru moments resulting in the observed MD coupling in this compound.