Study On Magnetization Dynamics In Multilayer Soft Magnetic Films With Stripe Domain Structur

In recent years,with the development of electronic products to miniaturization,integration and high frequency,magnetic materials must not only meet the high frequency requirements,but also have low loss and low cost.Soft magnetic films are widely used in inductor,magnetic field sensor and motor because of their high frequency magnetic properties,such as easy magnetization,easy demagnetization,low energy loss and high saturation magnetization.The domain structures of soft magnetic films with in-plane uniaxial anisotropy are dominated by single domain and in-plane closed domain.The magnetic moment of the soft magnetic film with stripe domain structure is periodically upward or downward from the film surface,and its magnetization dynamics also shows many resonance modes,such as acoustic,optical and spin-wave resonance modes.In this paper,Ni Fe thin film is the main research object,the research contents are as follows:1.The domain structure and high frequency magnetic properties of Ni Fe films with different thickness were studied.The thickness of Ni Fe films increased from 50 nm to 500 nm.The in-plane domain structure of the thin films from 50 nm to 200 nm and the stripe domain structure of the thin films from 300 nm to 500 nm were obtained from the Magnetic force microscope results.In in-plane domain films,there are two resonance peaks,the low-frequency one is ferromagnetic resonance caused by in-plane uniaxial anisotropy,and the high-frequency one is vertical spin standing wave.In the stripe domain films,it is considered that the low frequency resonance is caused by the domain resonance and the high frequency resonance is caused by the domain wall resonance.2.The effect of the thickness of Ru film on the stripe-free domain Ru/Ni Fe(100nm)bilayers was investigated.In dynamic magnetic properties,both the stripless domain Ru/Ni Fe bilayer films and the single-layer 100 nm Ni Fe films have two resonance peaks,the existence of Ru in the non-ferromagnetic layer increases the frequency of the low-frequency resonance induced by in-plane uniaxial anisotropy,the frequency of the high frequency resonance peak caused by the vertical spin standing wave is reduced.3.The influence of the thickness of Ru film on the stripe domain Ru/Ni Fe(350nm)bilayers was investigated.The grain size of Ru film with thickness of 30 nm is the smallest,the coercivity is the smallest,the remanence ratio is the largest,and the damping is the largest.In dynamic magnetic properties,the presence of Ru in the non-ferromagnetic layer increases the frequency of the two resonance peaks in the streaked domain Ru/Ni Fe bilayer compared with that in the monolayer 350 nm Ni Fe film,the frequency of the two resonance peaks in the optical branch mode is reduced.4.The influence of the thickness of the non-ferromagnetic layer Ru or ferromagnetic layer Co on the striated domain Co/Ru/Ni Fe three-layer films is studied.When the thickness of Ru film is less than 5 nm or the thickness of Co film is 100 nm,the magnetic moment in Co will affect the magnetic moment arrangement of stripe domains in Ni Fe film.The width of the fringe domain is inversely proportional to the frequency due to the intensity of the exchange coupling.