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

[摘要] 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 Pr0.5Sr0.5-xCaxMnO3 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-N. On the other hand, below T, 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. (C) 2000 Elsevier Science B.V. All rights reserved.

[发布日期] 2000-11-01

[关键词] charge ordering;thermoelectric power;magnetic ordering