Low Temperature Physics: 36, 741 (2010); https://doi.org/10.1063/1.3490860 (6 pages)
Fizika Nizkikh Temperatur: Volume 36, Number 8-9 (August 2010), p. 933-940 ( to contents , go back )
Effects of cross correlations between inhomogeneities on the spectrum and damping of spin and elastic waves
V.A. Ignatchenko and D.S. Polukhin
L.V. Kirensky Institute of Physics, Siberian Branch of Russian Academy of Sciences Krasnoyarsk 660036, Russia
Received December 25, 2009
Laws of dispersion and damping of spin waves in a ferromagnet with inhomogeneities of the exchange and magnetic-anisotropy parameters, as well as elastic waves in an isotropic medium with inhomogeneities of the density of material and elastic force constants are studied with taking into account cross correlations between these inhomogeneities. The general law that is independent of the wave nature is established: effects of cross correlations between inhomogeneities of any two material parameters on the wave spectrum are determined by the fact whether both these parameters belong to the same part of the Hamiltonian (that is, both are related to the kinetic part or to the potential one) or they belong to the different parts of the Hamiltonian. In the first case the positive cross correlations lead to a more dramatic modification of the dispersion law and an increase in wave damping, and in the second case to the decrease of these characteristics. Correspondingly, the negative cross correlations in the each of these cases lead to inverse effects. A qualitative explanation of this law is given.
PACS: 75.30.Ds Spin waves;
Key words: spin waves, elastic waves, inhomogeneities, correlations, cross correlations, dispersion, damping.