Structural and magnetic properties of SmCo5/Co exchange coupled nanocomposite thin films

Abstract

We investigated the structural and magnetic properties of SmCo5/Co exchange coupled nanocomposite thin films grown by magnetron sputtering from Sm and Co multitargets successively. The growth of the films was carried out at elevated substrate temperature followed by in situ annealing. On Si (100) substrate, X-ray diffraction confirms the formation of textured (110) SmCo5 hard phase, whereas on MgO(110) substrate, the diffraction pattern shows the epitaxial growth of SmCo5 phase with crystalline orientation along [100] direction. Secondary Ion Mass Spectroscopy reveals the structural transformation from multilayered (Sm/Co) to SmCo5/Co nano-composite films due to high reactivity of Sm at elevated temperature. Transmission electron microscopy indicates the existence of nanocrystalline phase of SmCo5 along with unreacted Co. Observed single phase behavior in magnetic hysteresis measurements indicates well exchange coupling between the soft and the hard phases in these nano-composite films. For samples with samarium layer thickness, tSm=3.2nm and cobalt layer thickness, tCo=11.4nm, the values of (BH)max were obtained as 20.1MGOe and 12.38MGOe with Hc value ∼3.0kOe grown on MgO and Si substrates, respectively.