Abstract
The spin-wave resonance (SWR) spectra, at X-band, has been studied in the temperature range 4.2–300 K for the reentrant Ni 76Mn 24 amorphous thin films coated with Ni and Ag layers. At room temperature, the spectra taken as a function of the dc field orientation have been extensively analyzed. The SWR spectra at all temperatures consist of both the volume and the surface modes. The spectra also exhibit hysteresis effects below the canting temperature, T f = 120 K. In addition, the macroscopic unidirectional anisotropy is induced along the cooling field direction when the sample is cooled down to 4.2 K through T f in a sufficiently high field. However, this anisotropy vanishes after a few cycles of the applied measurement fields, whereas this anisotropy is quite stable in the polycrystalline specimens. It was concluded that introducing the uniaxial volume anisotropy energy density up to the forth order only, E ani = - K 1 cos 2θ - K 2 cos 4θ, into the Landau-Lifshitz dynamic equation of motion for magnetization, where θ is the angle between the magnetization and film normal, would account for the observed angular behaviour of the spectra. Using the Rado-Weertman general exchange boundary condition with the surface energy density, E s = k s cos 2θ, we have derived an expression for spin wave absorption curves with Bloch type damping. The surface and bulk anisotropy constants, k s, K 1, K 2, the exchange stiffness constant, A, and damping parameter, 1/ T 2, have all been deduced by comparing the simulated theoretical absorption curves to the experimental ones. It was also found that the bulk mainly has an easy axis perpendicular anisotropy and a relatively weak easy plane shaped anisotropy, while the surface anisotropy essentially has as easy plane nature.
Published Version
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
