Electron paramagnetic resonance of cerium and alkali-doped manganites: a tool for fast characterization within a combinatorial chemistry approach

Cerium, sodium and potassium ions have been substituted to lanthanum and strontium within the series La1−xAxMnO3, starting from the composition La0.8Sr0.2MnO3. The temperature of transition from the high-temperature paramagnetic ‘insulating’ phase to the low-temperature ferromagnetic conducting phase has been studied versus composition by electron paramagnetic resonance. It is shown that, in addition to the resonant line near g equal to 2, characteristic of the paramagnetic phase, a lower-field asymmetric signal appears upon cooling in the ferromagnetic phase. The onset of this low-field additional signal scales with that of magnetization, is ascribed, therefore, to ferromagnetic resonances.