Structure, magnetic and dielectric properties of BaTiO₃-Co multi-layer nano-composite films

The BTO-Co multi-layer nano-composite films have been deposited successfully, which consist of amorphous BTO layers and Co nano-particles layers. By controlling Co layer thickness from 6.3 to 0.3 nm, the resistivity of BTO-Co films increases from 10⁰ to 10⁶ μΩ m. And the magnetization of films changes from 0.73 to 0.01 T. Noteworthy, when the Co layer thickness is 2.5 nm, the films show superparamagnetic properties. HRTEM observation clearly shows that these films have the nanometer-sized metal Co particles of around 2 nm in diameters and a homogeneous dispersion. With lower Co layer thickness, the BTO-Co films exhibit high electrical resistivity. The dielectric constant tested at 1 kHz of these BTO-Co films increases from about 10-40, by controlling the Co layer thickness.