学术沙龙2014年第二场主题报告定于4月11日（周五）下午16:30在物理楼5004报告厅举行，报告人为低维所柴国志老师，届时请各位老师参加。

报告摘要：

Rotatable anisotropy in magnetic thin films is a special type of anisotropy that can only be detected by high frequency measurement other than the traditional VSM B~H loops measurement. Up to now, it can be found in three types of magnetic thin films: (1) thin film with rotatable stripe domain structure, (2) antiferromagnetic/ferromagnetic multilayers, (3) thin film with strong exchange coupling interactions. The following types of magnetic thin films with rotatable anisotropy have been studied. In ferrite doped CoFe thin films, the resonance frequency with 4.5 GHz can be achieved in any direction of the film plane. The high resonance frequency is driven by the rotatable magnetic anisotropy propagated from the exchange coupling between rotatable ferrimagnetic spins and the ferromagnetic grains⁴. Combine with the rotatable stripe domain structure, the resonance frequency of the film possess zero-field ferromagnetic resonance frequency above 5 GHzafter increasing the thickness of thin film larger than 180 nm. By using the Ta buffer layer, the in plane high frequency permeability can further be optimized to 22 and the resonance frequency will reach 6.4GHz for films with the optimization parameters. As the direction in rotatable anisotropyare angular tunable, we combine the rotatable anisotropy and uniaxial anisotropy (arising from the oblique deposition) in the CoFeBSm thin film. The direction of easy axis can be rotated and the value of resonance frequency can been tuned from 3.8 GHz to 6.4 GHz and by applying a saturated magnetic field in film plane. These results may have a great implication for the tunable microwave magnetic devices.