Nano-structured exchange-spring hard magnetic thin films

In exchange coupled magnets, the length scale of the soft phase is limited to twice the domain wall thickness of the hard phase. We investigated the structural and magnetic properties of SmCo5/Co exchange coupled multilayers grown by magnetron sputtering from Sm and Co targets successively at elevated substrate temperature and subsequent in-situ annealing. X-ray diffraction indicates the formation of polycrystalline SmCo5 hard phase. Formation of hard/soft multilayered structure was confirmed through transmission electron microscopy. Magnetic hysteresis measurements shows single phase like behaviour, which indicates the soft layer (Co) is well exchange coupled with the neighbouring hard phase of SmCo5. Maximum energy product of 17.1 MGOe with Hc ~ 3.02 kOe was obtained