Study On The Anisotropic Magnetoresistance And Magnetic Properties Of Permalloy Thin Films Through Growth On Seed Layer Of (Ni_0.82Fe_0.18)_1-xNb_x

In this thesis, we explore the approach to improving the anisotropicmagnetoresistance (AMR ) and magnetic properties of permalloy (Ni0.82Fe0.18) films for adapting to the appliance of high sensitive magnetic heads and sensor . First, employing a new material (Ni0.82Fe0.18)1-xNbx as seed layer , we prepare a series of thin films of (Ni0.82Fe0.18)1-xNbx(dnm)/ Ni0.82Fe0.18(tnm)/Ta(3nm) by sputtering under direct current and an applied magnetic field, and measure the magnetorresistance curve, magnetic hysteresis and texture of the films. Second, we discuss the influence of the Nb percent concentration x and the thickness of seed layer d to the AMR and magnetic properties of thin films, and make a comparison with the films with Ta seed layer. Finally, we analyze the possible mechanism for the seed layer to influence the AMR and magnetic properties in the films. Based the experiments and analyses, we may make the following conclusions:(1) The AMR depends significantly on the Nb percent concentration x . The AMRbegin to increases, and then decreases with increasing x, the maximum AMR was observed with x=27.1%. Similarly, the AMR begin to increase and then decrease with increasing the thickness d of the seed layer, and has a maximum value at a critical thickness d of 5.32nm. Compared to the permalloy films deposited on Ta seed layer ,the AMR enhancement of 10%-46% is observed in the permallay films deposited on (Ni0.82Fe0.18)1-xNbx seed layer.(2) The coercivity Hc1 obtained for magnetic field H applied paralley to the easyaxis is large than Hc2 for H applied perpendicular to the in-plane easy axis, and both of coercivity are consistent with the change of x. Saturation magnetization Ms increases and then reduce with increasing x, and the Hc1 and Hc1 are both relatively little, but the maximum of Ms is observed with x=27.1%. The seed layer thickness doesn't lead to the evident change of the magnetic properties of the films. The coercivity is slightly smaller for the films deposited on (Ni0.82Fe0.18)1-xNbx seed layer than on Ta seed layer , but Ms is larger. The Ms increases with increasing permalloy thickness t, and the Ms enhancement of 20% is observed for the 40 nm thick permalloy films deposited on (Ni0.82Fe0.18)1-xNbx seed layer , compared to the films deposited on Ta seed layer.(3) The x-ray diffraction shows that the (Ni0.82Fe0.18)1-xNbx seed layer causes the formation of large (111) textured crystal grains in the permalloy thin film, and theinterface between these two layers is quite smooth. These both increase the Ap andreduce the resistance 0, which lead to the AMR coefficient enhancement in thepermalloy film.In addition, we do primary analysis to the magnetic properties of the films using Heisenberg model. It is shown that the Ms decreases with decreasing the thickness of films, which is in agreement with the predictions of the experiments.That high anisotropic magnetoresistance and well magnetic properties in the permalloy thin films deposited on (Ni0.82Fe0.18)1.xNbx seed layer indicates that the (Ni0.82Fe0.18)1-xNbx may be a new seed layer instead of the Ta seed layer.