Effect of working pressure on the properties of BaTiO_3-CoFe_2O_4 composite films deposited on STO (100) by PLD

摘要

The BaTiO_3-CoFe_2O_4 (BTO-CFO) composite films were grown on SrTiO_3 (STO) (100) substrates at 750℃ under various working pressures by pulsed laser deposition. The composite film grew into a supersaturated single phase at the working pressure of 10 mTorr, BTO and CFO (00 1) oriented hetero-epitaxial films on STO (100) at 100 mTorr, and a polycrystalline composite film at 500 mTorr. The slow growth rate at high working pressure led to the phase separation in the composite film. The CFO was compressively strained along out-of-plane due to the lattice mismatch with the BTO matrix phase. The BTO-CFO composite film grown at 100 mTorr showed reversible switching of ferroelectric polarization and magnetic hysteresis with strong magnetic anisotropy.