Study On Exchange Bias Of [PtCo]/IrMn System With Two-Directional Isotropy

The exchange bias of ferromagnetic(FM)/antiferromagnetic(AFM)film systems has been of great interests and plays an important role in magnetoelectronic technology.However,the physical mechanism of this effect is still unclear.Among the questions relative to exchange bias,the comparison between perpendicular and in-plane exchange bias is a key issue.The ever reported investigations about this topic give a series of contradictory results which are usually related to the FM anisotropy,for example,in ever reported perpendicular exchange bias systems the materials with strong perpendicular anisotropy were adopted as the FM layers,however,it is still under debate that how the FM anisotropy affect exchange bias of various directions.On the other hand,the atomic diffusion in thermal treatment is thought to significantly influence the exchange.In this dissertation,[Pt/Co]/IrMn multilayers were prepared and the anisotropy is studied by analyzing the remanence state.The sample with two-directional isotropy is selected by finely adjusting the thickness of Co layers,then the exchange bias is induced by field cooling from roomtemperature to low temperature in order to avoid the Mn atomic diffusion.By measuring the hysteresis loops at low temperature.We find that the perpendicular exchange bias is larger than the in-plane exchange bias and the spin flop coupling is absent after field cooling.The comparison of exchange bias along the two directions is modeled based on the uncompensated units in the growth plane.