We report measurements of thermopower and resistivity as a function of temperature on bilayered (Formula presented) ceramics treated in different atmosphere in (Formula presented) and (Formula presented) Chemical titration is used to determine both valence of manganese and content of oxygen. As the sample is annealed in nitrogen, the resistivity of (Formula presented) reduces; the peak resistivity shifts to a higher temperature; the magnetoresistance ratio is enhanced; and the thermopower shifts to a more negative value over the investigated temperature range as compared to the sample annealed in oxygen. These results show that annealing samples in flowing nitrogen has the same effect as the pressure-induced shift of transport behavior. In addition, thermopower data of our ceramic materials resemble those within the ab plane of a single crystal. Transport data will be discussed in terms of the polaron hopping.
|Number of pages||4|
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|Publication status||Published - 2000 Jan 1|
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics