Stable self-polarization in Nd and Ti codoped BiFeO3 films

Nd (3 %) and Ti (2 %) codoped BiFeO3 (BNFTO) films with different layer and film thicknesses were deposited on LaNiO3(100)/Si substrates using a metal organic decomposition method. The BNFTO films show a highly (100)-preferred orientation. The hysteresis loops of both films are asymmetric with negatively imprinted polarizations, suggesting that both samples are self-polarized regardless of the layer and film thicknesses. More importantly, the P-E hysteresis loops for both films can recover to their asymmetric shapes after high-field measurements, indicating the self-polarizations are quite stable. These results are explained based on the stabilization of the defect complexes. The effects of the self-polarization on the leakage, dielectric and piezoelectric properties of the BNFTO films are investigated.