Electronic transport and magnetic properties in (La1−xGdx)0.67 Ca0.33MnOδ perovskites

Polycrystalline samples of La-Ca-Mn-O doped with Gd have been prepared. We have systematically examined their electronic transport, low-field magnetoresistance, and magnetization behaviors in a series of (La1−xGdx)0.67Ca0.33MnOδ with 0.10≤x≤1.00. The maximum magnetoresistance ratio at B=0.85 T with (R0−RB)/R0=92.5% occurs approximately at x=0.3. It is also found that the Gd-doped samples show a novel memory effect. The effects of gadolinium ion composition on the electric and magnetoresistance behaviors of manganese perovskites (La1−xGdx)0.67Ca0.33MnOδ could arise as from changes in the average ionic radius of the La site 〈rA〉.