New perpendicular media by engineering the thermal stability and writing capability separately

We experimentally demonstrated two novel approaches to tune the thermal stability (K_uV/k_BT) and coercivity of perpendicular media separately to alleviate writing field limitation of perpendicular magnetic recording. The well-exchange decoupled magnetic grain is engineered into two parts: magnetic hard and magnetic soft. The first approach is to control the exchange coupling strength to a proper value thus the soft region of grain will switch first with an external field and apply a torque to help the switch of the hard region, which has been proposed theoretically and demonstrated experimentally. The second approach is to use the pure Zeeman energy from soft region of grain to help the switching of hard region of grain.