Date of Award
1995
Degree Type
Dissertation
Degree Name
Doctor of Philosophy
Abstract
In recent years a considerable research effort has been put into the understanding of the physical properties of quasi-two-dimensional magnetic systems. Theoretical investigations help to explain many current experimental results. The aim of this thesis is to study dynamic and critical properties of certain quasi-two-dimensional magnetic systems.;In the first part of the thesis (Chapters 2 and 3) the Handscomb Monte-Carlo method is applied to investigate the critical behavior of the S = {dollar}1\over 2{dollar} Heisenberg ferromagnetic film with the number of monolayers L {dollar}\le{dollar} 3. We confirm the renormalization group results for the two-dimensional model for a wide range of temperatures and report the effectively two-dimensional type of critical behavior for the films with L = 2 and L = 3.;The second part of the thesis (Chapters 4 and 5) is devoted to the development of an analytic theory of the dipole-exchange spin waves and their Brillouin light-scattering spectra in perpendicularly-magnetized magnetic films and multilayers. The time-dependent Green function technique is applied. The influence of the pinning parameter value on the magnon dipole-exchange spectrum of a single film in the case of near degeneracy of the surface mode and the nearest bulk mode is discussed. The dependences of the integrated light scattering intensities on the pinning parameter are calculated. The degeneracy is shown to have strong influence on the dispersion relationships for EuO films, having less importance in the case of iron films.;Next the theory is extended to the case of an exchange coupled magnetic double layer (two magnetic films separated by a non-magnetic spacer). The interlayer exchange coupling is shown to renormalize the pinning parameter at the interface between the magnetic film and the spacer for the antisymmetric SW modes.;Then we treat the case of a multilayer, consisting of a number of similar ferromagnetic layers separated by nonmagnetic spacers. The dipole-dipole and exchange coupling are included within the magnetic layers and between them. We present a semi-empirical theory for the spin wave spectra in the multilayer structures and discuss the Brillouin light scattering from spin waves in such structures.
Recommended Citation
Rojdestvenski, Igor V., "Dynamics And Thermodynamics Of The Quasi-two Dimensional Magnetic Systems" (1995). Digitized Theses. 2574.
https://ir.lib.uwo.ca/digitizedtheses/2574