CRITICAL-BEHAVIOR OF MAGNETORESISTIVITY IN LA2 3CA1/3MNO3/

The electrical resistivity has been measured in ceramic La2/3Ca1/3MnO3 as a function of temperature and magnetic field, including the vicini ty of the Curie temperature T-C congruent to 267 K and down to low fie lds. We found that the field dependence of the magnetoresistance Delta rho/rho reveals peculiar features close to T-C, unknown in convention al ferromagnets. Particularly, a finite linear response in field, besi des the usual quadratic term, is found above T-C. We propose that this behavior is due to the coexistence of two different types of magnetic fluctuations, related to itinerant and localized charge carriers. (C) 1997 American Institute of Physics.