(Formula presented) with (Formula presented) 0.06, and 0.11 was prepared by the Pechini citrate gel process at 1100 °C. Oxygen defects were created by quenching the sample from high temperature. Chemical analysis and x-ray absorption show that the formal valence of Mn in (Formula presented) is close to 4+, and that Mn(III) is created in the quenched samples. Moreover the x-ray absorption near-edge spectra results support the creation of two Mn(III) five coordinate sites for each O vacancy. (Formula presented) (Formula presented) are n-type semiconductors and order antiferromagnatically with Néel temperatures close to 125 K. The activation energy decreases with increasing δ. A relatively large (∼40%) negative magnetoresistance (MR) is observed for (Formula presented) This result shows that a substantial MR can occur in these G-type antiferromagnetic materials.
|Original language||English (US)|
|Number of pages||5|
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|State||Published - 1999|
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics