NMR probe of phase segregation in electron doped mixed valence manganites

A Mn-55 and La-139 NMR study of Lao(0.35)Ca(0.65)MnO(3) is reported. The ze ro field Mn-55 spectra consist of two lines centered at 290 and 375 MHz. Th eir behavior under an applied magnetic field makes it possible to attribute them to regions of antiferromagnetically and ferromagnetically coupled kin spins, respectively. This gives evidence for the existence of electronic p hase segregation of microscopic ferromagnetic regions of double exchange co upled Mn spins over a charge ordered antiferromagnetic background. The beha vior of these ferromagnetic regions in the applied magnetic field is relate d to the magnetoresistive properties of the manganites.