A Green's function formalism is used to calculate the spectrum of excitations of two neighboring impurities implanted in a semi-infinite ferromagnetic. The equations of motion for the Green's functions are determined in the framework of the Ising model in a transverse field and results are given for the effect of the exchange coupling, position and orientation of the impurities on the spectra of localized spin wave modes.
A Green's function method is used to obtain the spectrum of spin excitations associated with a linear array of magnetic impurities implanted in a ferromagnetic thin film. The equations of motion for the Green's functions of the anisotropic film are written in the framework of the Ising model in a transverse field. The frequencies of localized modes are calculated as a function of the interaction parameters for the exchange coupling between impurity-spin pairs, host-spin pairs, and impurity-host neighbors, as well as the effective field parameter at the impurity sites.
A Green's function formalism is used to calculate the spectrum of localized modes of an impurity layer implanted within a ferromagnetic thin film. The equations of motion for the Green's functions are determined in the framework of the Ising model in a transverse field. We show that depending on the thickness, exchange and effective field parameters, there is a "crossover" effect between the surface modes and impurity localized modes. For thicker films the results show that the degeneracy of the surface modes can be lifted by the presence of an impurity layer.
a b s t r a c tA Green's function method is used to obtain the spectrum of excitations of two neighboring impurities in a semi-infinite ferromagnet. The equations of motion for Green's functions are determined in the framework of the Heisenberg model. The energies of non-resonant localized modes are calculated as a function of the interaction parameters for the exchange coupling between impurity-spin pairs, hostspin pairs, and impurity-host neighbors, as well as the effective field parameter at the impurity sites. With two impurities the system is less symmetric and has more localized modes when compared with a single impurity case.
The surface spin wave branches in ferromagnetic films are studied using a microscopic theory which considers both magnetic dipole-dipole and Heisenberg exchange interactions. The dipole terms are expressed in a Hamiltonian formalism, and the dipole sums are calculated in a rapidly convergent form.The Damon-Eshbach surface modes are analyzed for different directions of the spin-wave propagation and also for different ratios of the strength of the dipole interactions relative to the exchange interactions. Numerical results are presented using parameters for Fe and GdCl 3 .
A Green’s function formalism is used to calculate the spectrum of localized states associated with an interstitial magnetic impurity in a semi-infinite ferromagnet described by the transverse Ising model. The nonresonant and resonant excitations of the system due to the impurity (i.e. the defect modes outside and inside, respectively, the region of the bulk and surface spin waves (SW)) are calculated numerically for the high-temperature phase. Two situations are analyzed, depending on the position of the interstitial impurity: the impurity is in the surface ([Formula: see text]) and the impurity is in the bulk region ([Formula: see text]).
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