The Soft Magnetic And High Frequency Properties Of [FeCoB/ZnO]_N Multilayer Thin Filmsdeposited By Oblique Sputtering

Along with the development of electronic information technology,many electromagnetic devices have a tendency of miniaturization,integration and being operated in higher frequency range(GHz).Otherwise,these developments also lead to serious electromagnetic interference,which makes a threat to our healthy.To satisfy different application,we have prepared four series of obliquely deposited samplas: FeCoB-Zn O granular thin film,[FeCoB(x nm)/ZnO(5 nm)]N multilayer films,[FeCoB(3 nm)/Zn O(t nm)]40 multilayer films and [FeCoB(x nm)/ZnO(8 nm)]n multilayer films by magnetron sputtering.We have studied how oblique deposition angle and the thickness of interlayer ZnO affect the properties of samples,respectively.Firstly,the in-plane unixal anisotropy field Hk can be effectively induced by oblique sputtering and the Hk of FeCoB-ZnO granular thin film can be tuned to 212 Oe and ferromagnetic resonance frequency fFMR increases to 5.3 GHz with the increased oblique angle(0°~56°).However,the damping factor ? is small and the width of half ferromagnetic resonance peak is beyond 1 GHz and both of them are almost constant.Thus,this can not only satisfy the requirement of high frequency,but also can be the potential material of suppressing electromagnetic interference and absorbing material.Secondly,the ZnO has been introduced to be interlayer to prepare FeCo B/ZnO multilayer films.The properties of multilayer films are superior to the FeCoB single thick layer.Besides,the covercicity decreases to 7.5 Oe from 69 Oe,the Hk increases to 280 Oe from 181 Oe and the fFMR is tuned to 3 GHz along with the increase number of interlayer.Moreover,the interlayer thickness t dependence of properties has been studied.It is found that covercivity is tuned to 5.6 Oe,while the Hk decreases firstly and then increases with the increasing t.The behavior of Hk can be interprated by ZnO which is a wide bandgap semiconductor and easy leading to ferromagnetic exchange coupling.But,the fFMR is insensitive to the t and change to 2.7 GHz from 2.3 GHz.Thus,this can satisfy the application that soft magnetic property can be effectively tuned in a wide frequency range.At last,during the study of [FeCoB(x nm)/ZnO(8 nm)]n multilayer films,we have found that the value of Acher's limit is bigger than it in single layer film and increases with the increasing period number n,which may be caused by interface anisotropy.So,it can be realized that ?s,Hk,fFMR can be effectively tuned in our study.