Magnetic and dielectric properties of the ruthenium double perovskites La₂MRuO₆ (M = Mg, Co, Ni, and Zn)

Abstract

Abstract Magnetic and dielectric properties of the ruthenium double perovskites La 2 MRuO 6 (M = Mg, Co, Ni, and Zn) were investigated. The magnetization measurements for M = Co and Ni showed the existence of magnetic order at 20–30 K. Though the oxides with M = Zn and Mg exhibit a deviation from the Curie–Weiss law, magnetic order was not clearly observed. The result of La 2 ZnRuO 6 was different from that previously reported, in which a ferromagnetic transition was found at around 165 K. The AC dielectric measurements for M = Co and Ni showed large dielectric constants (typically larger than 1000) at around room temperature, suggesting both the formation of short‐ranged polar regions and the magnetic origin of large dielectric constant. In addition, two peaks were found for the temperature dependence of the tan δ component for La 2 NiRuO 6 . The behavior suggests the existence of two different polar regions. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)