Anomalous Nernst Effect in Perovskite La_0.5Ca_0.5CoO₃

We report the occurrence of the anomalous Nernst effect (ANE) in polycrystalline perovskite La _0.5 Ca _0.5 CoO ₃ . The sample is ferromagnetic (FM) below $T_{C}$ = 147 K and resistivity shows non-metallic behavior above and below $T_{C}$ with only a small negative magnetoresistance (MR) (~2%) around $T_{C}$ . The field dependence of magnetization at 10 K shows large hysteresis with a coercive field of 6 kOe but a small magnetization ~ $0.64 ~\mu _{B}$ /Co even in a field of 50 kOe, which indicates the presence of magnetically heterogeneous ground state consisting of FM and non-FM phases. The field dependence of the Nernst thermopower ( $S_{xy}$ ) at low temperatures shows complete saturation, but the magnetization does not. This indicates that the ANE in La _0.5 Ca _0.5 CoO ₃ depends only on the transport properties of the FM phase, while it is not affected by the non-FM phase. Due to the higher value of remnant $S_{xy}$ , the magnetized polycrystalline sample exhibits ANE in the absence of an external magnetic field.