Preparation And Properties Of NiFe And NiFe-Cu-NiFe GMI Thin Films

NiFe thin films and NiFe-Cu-NiFe thin films were fabricated by a direction-current (DC) magnetron sputtering system. The phase structures of different NiFe thin films were studied by using grazing incidence X-ray analysis (GIXA). The texture and residual stress of different NiFe thin films were measured byωscan of X-ray diffraction (XRD) and 2θscan with differentω.The thicknesses of different thin films were characterized by means of small angle X-ray scattering (SAXS) technique. By using scan electron microscope (SEM) measured transect of thin films. The magnetic properties of NiFe thin films were measured by means of vibrating sample magnetometer (VSM). In addition, the giant magneto impedance (GMI) effects of sandwiched thin films were also measured.XRD diffraction pattern indicated that thin films were made of Ni-Fe admixture. When sputtering bias voltage was 50V and sputtering time was 120min, better thin flims were obtained. When anneal temperature was 400℃, thin films were still made of Ni-Fe admixture. When anneal temperature was 450℃or higher, FeNi3 instead of Ni-Fe admixture was appeared in the thin films.X-ray diffraction and SEM measured thin films'thicknesses. The higher the sputtering bias was, or the longer the sputtering time was, the thicker the thicknesses were.Meterage of texture so that the thin films were prepared at different sputtering bias voltage, only the film had better FeNi3 (111) texture when sputtering bias volage was 70V and anneal temperature was 450℃. When sputtering bias voltage was less than 70V, there was no texture in the thin films. For the flims which were prepared at 50V, there was no texture exist when anneal temperatures were 400℃,450℃and 500℃.The higher the sputtering bias voltage was, the bigger the residual stress was. When sputtering bias voltage was 50V, the residual stress was biggest. If sputtering bias voltage kept up becoming bigger, the residual stress became smaller and smaller.The numbers researched magnetic properties and GMI properties, and dependence between magnetic properties and structure was obtained. Meterage of magnetic properties of thin films were prepared at different sputtering bias voltage indicate that saturated magnetic quadrature became bigger when sputtering bias voltage became bigger, and when sputtering bias voltage achieved 50V, saturated magnetic quadrature was biggest, after that it became small though sputtering bias voltage still became big. For coercive force, except it was smallest when sputtering bias voltage was 50V, at other puttering bias voltage, there was no change. Higher sputtering air pressure (2.0Pa) and lower sputtering air pressure (1.0Pa) had the different effect for thin film'coercive force.For one layer thin films, the thicker the thickness was, the stronger the GMI effect was, the bigger the values of magnetic field when peak values of curve were biggest were. When sputtering time was 120min, GMI achieved 20.7%. For sandwiched thin films, GMI effect was stronger than that of one layer thin films and values of magnetic field was much smaller, just 10Oe.