Using different Mn-oxides to influence the magnetic anisotropy of FePt in bilayers with little change of the exchange bias field

摘要

We have investigated the exchange coupling between a bottom FePt thin film layer capped with different Mn-oxides. Results have shown that the magnetization reversal of the soft FePt layer is influenced strongly by the capped Mn-oxide layer (Mn, MnO, and Mn_3O_4), as revealed by the enhanced coercivities. Typical temperature dependent magnetization between zero-field cooled (ZFC) and field cooled (FC) scans was observed in the Mn-oxide (8%O_2/Ar)/FePt bilayer that exhibited a blocking temperature (T_B～120K) close to the Neel temperature, T_N, of MnO. However, the Mn/FePt bilayer exhibited unusual temperature dependent of M vs. T, implying that intermixing between Mn and FePt interfaces formed an AF FeMn that may have enabled a high irreversibility temperature (T_(irr) ～ 400 K) compared to almost identical ZFC and FC curves from weaker exchange coupling between FePt and the Mn_3O_4 created with 21 and 30%O_2/Ar deposition conditions.