GIANT MAGNETORESISTANCE IN La0.6Pb0.4Mn(1−x)TixO3 FILMS: ENHANCEMENT OF MAGNETORESISTANCE DUE TO Ti4+ SUBSTITUTION IN Mn4+ SITES†

Nonmagnetic Ti4+ ion is substituted for Mn4+ in La0.6Pb0.4MnO3. The resulting La0.6Pb0.4Mn(1−x)TixO3 (0 ≤ × ≤ 0.3) crystallizes in rhombohedral structure. The insulator-to-metal transition temperature decreases from 320 K to 92 K as x is varied from 0 to 0.09. Epitaxial films for the compositions x = 0, 0.03, 0.05, and 0.07 are fabricated by pulsed-laser deposition. Magnetoresistance at 6 T is enhanced from 38% for x = 0 to 75% for x = 0.07. The presence of Ti4+ (d0) ion decreases the Mn-Mn interaction through oxygen and thereby affects the resistivity and magnetoresistance of La0.6Pb0.4MnO3. © 1997 Elsevier Science Ltd