| The multilayer film has been focus in the field of anisotropic material research. To meet modern industry's demand for device size, the magnetic properties of NiFe films should be improved when the thickness of NiFe films is as thin as possible. This experiment has mainly studied the ways to improve the AMR value of NiFe films according to practical requirement. A series of films are prepared: Ta(4nm)/Y2O3(t)/Ni81Fe19(20nm)/Y2O3(t)/Ta(3nm), Ta(4nm)/Ag(t)/Ni81Fe19(20nm)/ Ag(t)/Ta(3nm) and Nb(t)/Ni81Fe19(20nm)/Nb(3nm). The AMR value, phase composition, magnetic hysteresis hoop and surface topography of Ni81Fe19 films were measured and analyzed by four-point probe technology, X-ray diffraction(XRD), vibrating sample magnetometer(VSM) and atomic force microscope(AFM), respectively. We analysis the effects of Y2O3 oxide intercalation thickness, special reflective layer Ag layer, the buffer layer Nb layer thickness and substrate temperature on the magnetic properties of NiFe film. We draw the following conclusions:(1) For the film: Ta(4nm)/Y2O3(t)/Ni81Fe19(20nm)/Y2O3(t)/Ta(3nm), the AMR value of the NiFe film will be affected significantly with the inserting Y2O3 layer.The AMR value increases quickly with t increasing in the beginning and then decreases when t>2.5. With 2.5nm of the inserting Y2O3 layer, the AMR value of 20 nm Ni81Fe19 film can reach the maximum 4.61%, which enhances 71.3% comparing without Y2O3 layer. The hysteresis loop analysis of NiFe film shows that the variation law of the saturated magnetic moment is same as the AMR value with the increasing of thickness of Y2O3 inserting layer. X-ray diffraction analysis shows that the Y2O3 inserting layer enhances the crystallization quality of Ni81Fe19 films and then reduces the membrane resistance and improves the AMR of NiFe films.(2) The AMR value of the film: Ta(4nm)/Ag(t)/Ni81Fe19(20nm)/Ag(t)/Ta(3nm) changes with the Ag layer thickness. When the Ag layer thickness t=1nm, the AMR value can reach the maximum 2.88%, which slightly increase a little comparing without Ag layer.(3) An appropriate thickness of buffer Nb layer can improve microstructure and magnetic properties of NiFe film. For the film: Nb(t)/Ni81Fe19(20nm)/Nb(3nm), the AMR value and magnetic sensitivity increases in the beginning and then decrease with Nb thickness t increasing. When t=3nm, the AMR value and magnetic sensitivity of the NiFe film can reach the maximum 3.61% and 4.53×10-3m·A respectively. The AMR value of Nb(3nm)/Ni81Fe19(20nm)/Nb(3nm) is 3.39% and it is 26 percent more than the AMR value of Ta(4nm)/Ni81Fe19(20nm)/Ta(3nm). Thus, Nb buffer layer works better than Ta buffer layer for improving magnetic properties. The substrate temperature also has a significant impact on the AMR value and other magnetic properties of the film: Nb(3nm)/Ni81Fe19(20nm)/Nb(3nm). When T?500?, the AMR value and magnetic sensitivity of the film increases with the increasing temperature. When T=500?,the AMR value and magnetic sensitivity can reach the maximum 3.76% and 7.49×10-3m·A respectively. On the other hand, the magnetic field saturation resistance and resistivity of the film decrease. When T=500?,the magnetic field saturation resistance and resistivity get the minimum 502A·m-1 and 1.8102×10-7?·m. When T>500?, the AMR value and magnetic sensitivity decrease, the magnetic field saturation resistance and resistivity increase. Therefore the magnetic properties of the NiFe film can be the best when T=500?. XRD and AFM image analysis show that an appropriate substrate temperature enhances the crystallization quality of NiFe films and then improves the AMR of NiFe films. |
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