The Investigation Of Rotatable Anisotropy In The Thin Film With Stripe Domain

Magnetic materials have extensively been used in magnetic electronic devices. With the improvement of the information transmission and the rapid processing speeds, such as the communication frequency of 4G mobile telephone has reached more than 3 GHz, the material which can respond the sensitive material signal in high frequency is imperative for future magnetic electronic device. Although high resonance frequency can be obtained in this thin film with in-plane uniaxial anisotropy, the microwave devices prepared by this material with uniaxial anisotropy respond the microwave magnetic field in only one direction. However, the microwave devices prepared by this thin film with stripe domain can regulate the high frequency property in any direction. The rotatable magnetic anisotropy exists in the thin film with stripe domain. In this paper, the magnetic film with stripe domain can be prepared by magnetron sputtering. The rotatable anisotropy is researched by the measurement of VSM, FMR, MFM, VNA etc.. Therefore, we obtained the following innovative conclusions:(1) Stripe domain structures were controlled by doping different concentrations of ferrite in FeNi films. With increasing concentration of doped ferrite, the width of stripe domain measured by MFM decreases. The perpendicular magnetic anisotropy field (H⊥) by analyzing data measured by FMR in different direction increases. Stripe domain disappears and bubble like features are observed with doping ferrite at 32% due to large H⊥. Moreover, increasing doping concentrations of ferrite realize the resonant frequency enhanced from 1.3 to 2.3 GHz.(2) With different oblique angles, rotatable anisotropy in ferrite doped FeNi thin film with stripe domain (SD) was investigated. Rotation of SD under an in-plane magnetic field along hard axis was measured by magnetic force microscopy, suggesting the existence of rotatable anisotropy. The in-plane effective field and rotatable anisotropy field Hrot were obtained by the measurement of FMR in different direction. As the oblique angle increases, an increase of Hrot from 305 Oe to 468 Oe was obtained and H⊥. increases accordingly. These results indicated a correlation between rotatable anisotropy and perpendicular anisotropy.(3) Based on these results above, taking into the rotatable anisotropy correlated with perpendicular magnetic anisotropy, we give the energy to simulate hysteresis loop. The energy contains Zeeman energy, in-plane uniaxial anisotropy energy, the first and second terms of perpendicular magnetic anisotropy energy and exchange energy. These results of numerical simulation manifest the rotatable anisotropy can be related to the perpendicular anisotropy.