Adjustable magnetic anisotropy and resonance frequency of patterned ferromagnetic films by laser etching

A simple laser etching method is utilized to adjust magnetic anisotropy and resonance frequency of patterned FeCo thin films from 12 to 700 Oe and from 1.0 to 8.2 GHz, respectively. The results show the demagnetization effect is yet evident when the strip widths vary from 0.05 mm to 1.00 mm. The magnetic anisotropy of the sample can be controlled by altering strip width and direction under the action of induced magnetic field. The resonance frequency of unpatterned films is 3.6 GHz. When strip direction is parallel to induced magnetic field direction, the resonance frequency of patterned films shifts to larger value with decreasing strip width. On the contrary, the resonance frequency decreases when strip direction is perpendicular to induced magnetic field direction. A shape anisotropy model based on the shape demagnetization effect is developed to estimate the effective in-plane uniaxial magnetic anisotropy. (C) 2012 Elsevier B.V. All rights reserved.