Abstract :
Magnetoresistance (MR) and magnetization (dc and ac) measurements have been carried out on the manganites, (La0.7−2xEux)(Ca0.3Srx)MnO3 (0.05≤x≤0.15), in the temperature range of 5–320 K. At 5 K, an unusually large MR of almost 98% is observed in the x=0.15 sample, nearly up to fields of 4–5 T. This large high-field MR occurs in the metallic region, far below the insulator–metal transition temperature, and does not vary linearly with applied field. The unusual magnetoresistance is explained in the light of various possibilities such as phase segregation, cluster spin–glass behavior, etc.
