Negative magnetoresistance of $(1-x)$La$_{0.7}$Sr$_{0.3}$MnO$_{3}$/$x$(GeO$_{2}$, Li$_{4}$P$_{2}$O$_{7}$) composite ceramics

Ceramics of $(1-x)$La$_{0.7}$Sr$_{0.3}$MnO$_{3}$/$x$(GeO$_{2}$) and $(1-x)$La$_{0.7}$Sr$_{0.3}$MnO$_{3}$/$x$(Li$_{4}$P$_{2}$ O$_{7}$) compositions with $x$ = 0.1–0.3 have been synthesized that possess high absolute values of isotropic negative magnetoresistance $MR$ at room temperature. In a composite containing 20 mass % GeO$_2$ as the barrier component, the negative magnetoresistance reaches $MR$ = 15% in a magnetic field of 18 kOe, while an analogous composite with Li$_{4}$P$_{2}$O$_{7}$ under identical conditions has $MR$ = 16%.