Ta/nd/ndfeb/nd/ta Multilayer Film Preparation And Magnetic Studies

NdFeB permanent magnet material has excellent magnetic properties,widely used in generators, automotive, medical equipment, and computers andother high-tech fields, and it is one of the important base materials whichsupport modern electronic information industry base. With electronic devicesand systems to micro, fine, thin, intelligent direction, the NdFeB permanent filmwill have good prospects for application in micro-motors, magnetic recording,sensors and microwave circuit.Ta/Nd/the NdFeB/Nd/Ta thin films were prepared by radio-frequencymagnetron sputtering with different thicknesses of NdFeB layer, and Nd layeron P-type Si （100） substrate and the films had650℃and750℃crystallizationprocessing. We used Scanning microscopy to observe the growth of the film, thesurface morphology of the films were analyzed by atomic force microscopy（AFM）, using X-ray diffraction （XRD） to study the phase structure of the film,using a vibrating sample magnetometer （VSM） test the film parallel andperpendicular to the direction of the hysteresis loop.Keep the thickness of the Ta layer of60nm and Nd layer thickness of250nm unchanged, the films had650℃for30min crystallization treatment, thecoercive force parallel and perpendicular to the direction of the films decreasefirst and then increase with the in the thickness of the NdFeB layer increase, andfinally decreased. The film has best magnetic property when the NdFeB thicknessis750nm,the coercivity of the parallel and perpendicular directions respectivelyis21.19kOe and19.44kOe, remanence ratio respectively0.87and0.68. The filmwith600nm NdFeB layer has best magnetic property after750°C crystallizationprocess, the coercivity of the parallel and perpendicular directions respectively is23.22kOe and17.56kOe, remanence ratio respectively0.84,0.62.Keep the thickness of the Ta layer of60nm and Nd layer thickness of250nm unchanged, the films had650℃for30min crystallization treatment, thecoercive force parallel to the film increase with the Nd layer thickness increases;the coercive force of the perpendicular direction increase first and then decrease with increasing of the Nd layer thickness. Parallel coercive force is the largestwith1000nm Nd layer thicknesss and showed as23.19kOe, but the verticalcoercive force direction of the film is small, as6.98kOe. This may be because theNd layer is too thick, affecting the vertical alig nment of the film. When the750℃crystallization treatment to the film and the Nd layer thickness is1000nm,its parallel coercivity increased to25.21kOe, but the vertical direction of thecoercive force is further reduced, only2.76kOe.We had hysteresisback line test under300K,320K,340K,360K,380K forthe Ta（100nm）/Nd（400nm）/NdFeB（600nm）/Nd（400nm）/Ta（100nm） filmsafter750℃crystallization treatment for30min. Found that the coercive forceof the film parallel and perpendicular direction decrease with increasing oftemperature. The temperature coefficient of the parallel and perpendicularcoercive force of the film respectively is-0.49%K^-1and-0.50%K^-1. Thethermal stability of the prepared films coercivity is superior to generalcommercial rare earth permanent magnet material.