Grain size distribution dependent magnetic and ferroelectric properties in sol–gel driven BiFeO 3 thin films

The effect of thickness induced grain size distribution on the magnetic and ferroelectric behaviour of sol–gel driven BiFeO 3 (BFO) thin films was investigated in this study. FESEM micrographs showed well-crystallized equiaxed grains with minimal porosity. The magnetization ( M ) versus magnetic field ( H ) indicated the well saturated hysteresis loops at 300 K. The saturation magnetization ( M s ) is found to decrease from 18.9 to 0.93 emu/cm 3 on increasing the film thickness from 156 to 388 nm. The high M s value obtained in the BFO films due to the uncompensated spins originated at grain boundary tends to decrease with the film thickness. At low temperature (10 K), non-saturated M – H loops are observed due to spin freezing effect. The dielectric and ferroelectric properties improve with better growth and densification of grains in the BFO thin films with increasing thickness.