Giant 1/f noise in perovskite manganites:: Evidence of the percolation threshold

We discovered an unprecedented magnitude of the 1/f noise near the Curie temperature (T-c) in low-T-c manganites. The scaling behavior of the 1/f noise and resistance provides strong evidence of the percolation nature of the ferromagnetic transition in the polycrystalline samples. The steplike changes of the resistance with temperature, observed for single crystals, suggest that the size of the ferromagnet ic domains depends on the size of crystallites.