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ABSTRACT
The Co/Pt multilayers with Pt and MgO/Pt underlayer were prepared by magnetron sputtering and the perpendicular magnetic anisotropy(PMA) of the multilayers were researched by the means of Anomalous Hall effect (AHE). The annealing effect study of Pt(1.0)/[Co(0.4)/Pt(0.8)]3(unit: nm) shows that the sample has pretty good thermal stability but the coercivity(HC) has little change. The experimental results show that the PMA and Hc of Co/Pt multilayers was improved greatly by the additional scattering of electrons induce from the amorphous insulator-metal interface of MgO-Pt. When MgO layer thickness(tMgO) is 4nm, the Hall resistance (RHall) of MgO(4)/Pt(1.0)/[Co(0.4)/Pt(0.8)]3 multilayer has a maximum value of 2.11Ω which is increased by 16%. Furthermore the Hc increases to 172Oe which is more than 1.5 times to Pt(1.0)/[Co(0.4)/Pt(0.8)]3 multilaye and the Hc meets the maximum value of 204Oe when tMgO is 2 nm. Annealing effects of MgO(4)/Pt(2)/Co(0.2)/Ni(0.4)/Co(0.2)/Pt(2) show that it has good thermal stability and the Hc reaches its maximum value of 438Oe at annealing temperature(TA) of 300°C. The multilayer begins to lose the PMA property at higher TA. The Hysteresis loop of MgO(4)/Pt(1.0)/[Co(0.4)/Pt(0.8)]3 multilayer annealed at 300°C was tested and the anisotropy constant(Keff) was obtained as 8.9 × 106 erg/cm3, which is about 4.45 times the Pt(1.0)/ [Co(0.4)/Pt(0.8)]3 multilayer. The PMA of Co/Pt multilayers is greatly enhanced by MgO/Pt interface and annealing treatment.
Funding
This study was financially supported by the National Natural Science Foundation of China (Grant No. 11174020, 51271211), and by Characteristic research team of Beijing Technology and Business University (Grant No. 19008001076).