Abstract :
The La0.7Ca0.3−xBaxMnO3 (x=0, 0.15, 0.3) manganites were studied by electron paramagnetic resonance (EPR). Temperature dependencies of EPR line intensity can be fitted by the deduced exponential decay I(T)=I0 exp(Ea/kBT) at more wide temperature range as compared with the Curie–Weiss law (Ea and kB are the activation energy and Boltzmann constant, respectively). A deviation of the EPR line intensity from the Curie–Weiss law near the Curie point indicates for the spin–lattice interaction in lanthanum manganites near that temperature. This interaction decreases at high temperatures. The exponential decay is valid in the conditions when the temperature dependence of EPR line width is proportional to the conductivity one.
