Shape Anisotropy Effect in the Ferromagnetic Resonance Experiment

Abstract

For magnetic moment, existence of spin and orbital angular momentum allows that the magnetic moment has instantaneous precession motion with a frequency, so called Larmor precession frequency, under the applied magnetic field. The precession motion of the spin is also affected by DC magnetic field component of the electromagnetic (EM) waves. When AC EM wave is externally applied perpendicular to DC magnetic field, and frequency of the AC wave is consistent with the Larmor precession frequency, the resonated precession motion of the spin absorbs the power of the microwave. Using the resonance phenomena of the spin precession motion with respect to the externally applied microwave, ferromagnetic resonance (FMR) technique enables to investigate the spin dynamics in the magnetic materials. It has been widely utilized for studies of physical properties of ferromagnetic thin films. On the other hands, there have been a few studies of spin dynamics in bulk ferromagnetic systems, such as ceramics and single crystal, using the FMR technique.[1] In case of the bulk system, various boundary condition as well as the intrinsic spin dynamics can affect the FMR spectra due to the geometric shape. In order to understand the extrinsic effect in FMR spectra, we have prepared Yttrium Iron Garnet ceramics and single crystals and systematically studies shape anisotropic effect in the FMR spectra.