Magnetic Properties Of Nickel Ferrite Films Deposited By Magnetron Sputtering At Room Temperature

Soft magnetic spinel ferrite has been widely used in electronic devices,communication equipment,computers and many other fields,due to its high resistivity,wide applicable frequency range,low loss and good chemical stability.With the development of devices moving towards miniaturization,integrated chip and high performance,soft magnetic ferrite also has the trend to be made into films.Ni-Zn ferrite is one of the best soft magnetic materials in high-frequency application.The resonance frequency of Ni-Zn ferrite films is supposed to have a break through due to bianisotropy picture.For spinel ferrite,since the magnetic properties depend on the structure,obtaining nickel ferrite films with good crystallinity becomes a key point.Thus,in this paper,the nickel ferrite thin films were fabricated by RF magnetron sputtering at room temperature.The structure,appearance and magnetic properties were measured by X-ray diffraction,scanning electron microscope,vibrating sample magnetometer and vector network analyzer.The research findings are as follows.1.Oriented polycrystalline Nickel ferrite(Ni Fe₂O₄)film deposited by magnetron sputtering at room temperature and its properties.The effect of sputtering conditions such as target distance,atmosphere,sputtering power and sputtering pressure,on the structure of nickel ferrite film were explored.As a result,single-phase polycrystalline nickel ferrite film with good crystallinity and preferred crystal orientation of(100)can be directly deposited on glass substrates by magnetron sputtering at room temperature,using the commercial target.2.Single crystal Nickel ferrite(Ni Fe₂O₄)film deposited by magnetron sputtering at room temperature and its properties.Single crystal nickel ferrite films(Ni Fe₂O₄)are directly deposited on single crystal substrates such as Sr Ti O₃,Mg O and PMNPT by magnetron sputtering at room temperature,using the self-made target,which hasn't been reported before,providing a new method for obtaining spinel single crystal ferrite films.The preparation process without heating also reduces the application limitations of single crystal nickel ferrite films in chip electronic devices.What's more,the single crystal nickel ferrite film with a thickness of 500 nm deposited on PMNPT(110)shows a saturation magnetization of 185 emu/cc at room temperature,and its resonance frequency increased to 4.95 GHz,which corresponds with the prediction of the Bianisotropic model.3.Polycrystalline Ni-Zn ferrite(Ni_0.3Zn_0.7Fe₂O₄)film deposited by magnetron sputtering at room temperature and its properties.Single-phase polycrystalline nickel zinc ferrite films with good crystallinity can also be directly deposited on silicon substrate by magnetron sputtering at room temperature,using the purchased target,which shows that the sputtering condition is common for spinel ferrite,especially for nickel zinc ferrite.The permeability of the film is about 7 and decreases at 3GHz.The resonance frequency is about 4.26 GHz.