Anisotropy of Percolation Threshold of BaTiO3-Ni0.5Zn0.5Fe2O4 Composite Films

A systematic study on the magnetic and electrical percolation phenomena of BaTiO3 (BTO)-NiZnF2O4 (NZFO) composite films is presented in this work with the purpose of simplifying the preparation process of high-performance 1-3-type multiferroic composite films. Results show that the percolation threshold of the composite films depends on the macroscopic dimension of the material. The low-dimensional nature of the composite films results in different percolation thresholds with topological transition in vertical and horizontal directions. BTO-NZFO composite films with a grain size of 15 nm and a thickness of 100 nm exhibited a percolation threshold of 0.18 in the normal direction and a percolation threshold of 0.48 in the horizontal direction. In light of this intriguing feature, a novel multiferroic composite film with 1-3 structure and strong magnetoelectric coupling was easily prepared by a 0-3 process via controlling the NZFO content in the region between two percolation thresholds.