Electrical transport and percolation in structural phase-separated manganites La1−xBaxMnO3

Microstructural studies show that manganites La1−xBaxMnO3 (0.33≤x≤0.95) begin structural phase separation into La0.67Ba0.33MnO3 and BaMnO3 for x>0.33. These composites form a cellularlike structure when the volume faction of La0.67Ba0.33MnO3 (fLBMO) is near the percolation threshold (fC). The percolation threshold (fC) for our composites is 0.18. This result is not consistent with the previous results, which prefer smaller percolation threshold value. This could be attributed to the contribution of grain boundaries. This grain-boundary contribution also induces the large low-temperature bump in electrical transport. The critical exponents t gained from the good fitting for the experimental data are 1.6 at 150 K and 1.7 at 300 K, which are in good agreement with the previous universal result: t=1.6–2.0 for the three dimensional space.