Electrical transport properties and magnetoresistance of La0.7Sr0.3MnO3:xZn1−yCoyO composites

The La_0.7Sr_0.3MnO₃:xZn_1-yCo_yO (x=0.0, 0.1, 0.2, 0.3, 0.4mo1, y=0.05) composites were prepared via a sol-gel process. The temperature dependence of the resistivity and magnetoresistance of the composites with different Zn_1-yCo_yO were investigated. X-ray diffraction reveals that both the compounds maintain their identities, that is, there is no evidence of reaction between the La_0.7Sr_0.3MnO₃ (LSMO) and Zn_0.95Co_0.50O. Magnetization is observed to decrease as the Zn_0.95Co_0.05 content is increased. Moreover, it is found that the change in MR is greater in the doped composites with x=0.1, 0.2, 0.3, as compared to pure LSMO. At the same time, on the addition of weak magnetic Zn_0.95Co_0.05O, the spin disorder is produced through the tunneling process at the grain boundaries and when a magnetic field is applied, the spin disorder is suppressed, resulting in a high MR at the low field 5 kOe.