Magneto-transport and magneto-dielectric effects in Bi-based perovskite manganites

Abstract

The study of the substitution of manganese by cobalt in the perovskite (LaBi)MnO₃ in view of discovering magneto-dielectric properties in manganites, has allowed the perovskite La_1.2Bi_0.8Mn_1.2Co_0.8O_6.02 to be selected. This phase is indeed ferromagnetic, like the parent phase La_1.2Bi_0.8Mn₂O_6.20, yet with a much higher T_C (181 K instead of 103 K). Moreover, it is a better insulator than the other members with an activation energy of 86 meV. Importantly, it exhibits a significant magneto-dielectric effect of around 0.25% at 80 K. Finally, it is also shown to exhibit magnetoresistance (MR) properties at low temperature, with MR values up to −19% at 125 K. These properties are explained on the basis of Mn⁴⁺/Co²⁺ ferromagnetic interactions, electronic phase separation and spin–lattice interactions.