Structural order, magnetic and intrinsic dielectric properties of magnetoelectric La2CoMnO6

Rare-earth manganites with a double perovskite structure play an important role in the field of multiferroics and magnetoelectrics as they encompass remarkable dielectric properties, semiconductivity and ferromagnetism near room temperature. In this family, La2CoMnO6 is one of the most investigated compounds partially due to its ferromagnetic Curie temperature reaching up to 235 K. Since their magnetic and dielectric properties are strongly influenced by the B-site ordering of Co and Mn ions, understanding and mitigating the sources of structural disorder becomes a crucial task in order to produce functional materials. In this paper, we present a series of La2CoMnO6 ceramics covering a broad spectrum of B-site orderings obtained by employing different calcination temperatures and synthesis conditions. Consequently, the magnetic and intrinsic dielectric properties, which depend on the ordering, change accordingly. Next, we show that the intrinsic dielectric constant of La2CoMnO6 is weakly dependent on the calcination temperature and we argue that the early observed colossal dielectric constant is of an extrinsic origin. Finally, we report reduced dielectric losses upon changing the calcination temperatures thus enabling a tool for enhancing the unloaded quality factor as demanded by dielectric resonator at microwave frequencies applications.