The influence of oxide seed layers on the magnetic properties and crystalline structures of hcp–Co80Pt20 perpendicular magnetic thin
films were investigated for magneto–optical chemical and biological sensing system. Cr–O, Al–doped ZnO (AZO) and Al2O3 films were used
as the oxide seed layers. The Cr–O layer was most effective to improve the perpendicular magnetic properties of Co–Pt. The Cr–O seed layer
produced the largest values of the interfacial perpendicular magnetic anisotropy (KS) and perpendicular magnetocrystalline anisotropy (KV).
The investigation in the crystalline and chemical bonding conditions suggested that the both perpendicular magnetic anisotropies were
originated from the interaction of Co and oxide at the Co–Pt/Cr–O interface. The improvements of KS and KV on the Cr–O seed layer are
attributed to the hybridization of Co–3d and O–2p orbits and the hcp(001)–CoPt crystal growth with self–orientation, respectively. We also
demonstrated the magneto–optical cavity effect on the Co–Pt perpendicular magnetic stacked films with the Cr–O intermediate layer. The
stacked films indicated a large magneto–optical response by optical interference and good perpendicular magnetic properties with an ideal
square shaped hysteresis loop.