Dielectric, Ferromagnetic Characteristics, and Room-Temperature Magnetodielectric Effects in Double Perovskite La_2CoMnO_6 Ceramics

摘要

The magnetic, dielectric, and magnetodielectric properties of La_2CoMnO_6 ceramics were evaluated together with the polarization-electric field hysteresis loops. The phase segregation consisting of ordered and disordered regions was determined in the present ceramics. The ordering of Co~(2+) and Mn~(4+) gave rise to ferromagnetic transition temperature as high as 210 K, while the disordering of Co~(3+) and Mn resulted in low ferromagnetic transition temperature of 80 and 150 K. The relaxor-like behavior combined with a giant dielectric constant (~ 105) was determined in La_2CoMnO_6 ceramics, which was attributed to the charge ordering of Co~(2+) and Mn~(4+). Owing to the mutual origin of magnetism and dielectric relaxation, La_2CoMnO_6 ceramics showed considerable magnetodielectric effects (~0.8% at 10 kOe) at room temperature.