Magnetization Damping in Microstructured Ferromagnetic Materials




Zhang, Lei

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The magnetization damping properties of square permalloy elements were characterized. These 20 nm-thick permalloy squares were deposited by the electron beam evaporation. Time resolved magneto-optic Kerr effect microscopy (TR-MOKE) was used to measure the magnetization evolution in the sample. By curve fitting in Matlab, I obtained the value of damping constant that is consistent with the reference paper. A Landau confi guration in the square permalloy sample leads to the different trends of the damping constant with external bias field. The damping constant in the bottom domain is found to decrease with increasing bias field while the damping constant in the top domain has been saturated into the minimum value. The decreasing tendency of magnetization precession frequencies is consistent with the Kittel equation modi fied with an anisotropic energy term. Additionally, FePt thin films and patterned CoFeB disks were investigated but neither yielded conclusive dynamic data.



Magnetization Damping, Microstructured Ferromagnetic Materials, TR-MOKE