Correlation between thermoelectric properties and magnetic phases in the charge-ordered Pr0.5Sr0.5−xCaxMnO3

Abstract We have performed measurements of thermoelectric power (TEP), electrical resistivity, DC magnetization and X-ray powder diffraction in polycrystalline samples of the charge-ordered manganite Pr 0.5 Sr 0.5− x Ca x MnO 3 for x =0, 0.1 and 0.2. All the studied samples revealed three magnetic phases: paramagnetic at high temperatures, ferromagnetic below T C down to T N , below which the antiferromagnetic phase is established. At the paramagnetic–ferromagnetic transition, the TEP presents a clear break, and the three samples show metallic resistivity below T C . On the other hand, below T N all the samples turn to an insulating-like resistivity, but the TEP shows striking differences between the x =0 sample and the other two. These differences are compatible with the different lattice and magnetic structures of the samples. These results support the idea that below T N a 2D-metal is present and no charge-order accompanies the A-type antiferromagnetic phase.