%0 Journal Article %1 Gumbs1980 %A Gumbs, G. %A Griffin, A. %D 1980 %J Surface Science %K imported %N 2-3 %P 669--693 %T Surface spin waves in a tight-binding itinerant-electron ferromagnet %U http://www.sciencedirect.com/science/article/B6TVX-46SPP5F-42/2/ac4bf3e4cba69e376870f6b6653d4b71 %V 91 %X We present the first theoretical study of surface spin waves in an itinerant-electron ferromagnet, using a single tight-binding band for d-electrons on a simple cubic lattice. All previous studies of bounded ferromagnets were based on a Heisenberg Hamiltonian with spins localized at sites. The surface is introduced in the Hubbard Hamiltonian by ignoring hopping between Wannier sites across a plane. Within a Wannier site representation, we set up the self-consistent field theory for the transverse spin-spin correlation function chi+-. When a ferromagnet has a planar boundary, chi+-. will exhibit a surface spin wave branch, in addition to the usual bulk spin wave modes. We solve the RPA integral equation for chi+- using a uniform spin polarization approximation for the static magnetization with classical specular scattering of electrons at the boundary. We find that a weakly damped surface branch splits off the top of the bulk spin continuum, rather than below as in the analogous Heisenberg model. The time-dependent magnetization associated with this mode is shown to be strongly localized within the first few surface layers, becoming more spread out as the static magnetization decreases. Our tight-binding Hubbard model with only on-site exchange leads to results very similar to those found by Griffin and Gumbs for a bounded electron gas model with an exchange interaction of finite range lambda if we take this to be equal to the lattice spacing.

@article{Gumbs1980, abstract = {We present the first theoretical study of surface spin waves in an itinerant-electron ferromagnet, using a single tight-binding band for d-electrons on a simple cubic lattice. All previous studies of bounded ferromagnets were based on a Heisenberg Hamiltonian with spins localized at sites. The surface is introduced in the Hubbard Hamiltonian by ignoring hopping between Wannier sites across a plane. Within a Wannier site representation, we set up the self-consistent field theory for the transverse spin-spin correlation function [chi]+-. When a ferromagnet has a planar boundary, [chi]+-. will exhibit a surface spin wave branch, in addition to the usual bulk spin wave modes. We solve the RPA integral equation for [chi]+- using a uniform spin polarization approximation for the static magnetization with classical specular scattering of electrons at the boundary. We find that a weakly damped surface branch splits off the top of the bulk spin continuum, rather than below as in the analogous Heisenberg model. The time-dependent magnetization associated with this mode is shown to be strongly localized within the first few surface layers, becoming more spread out as the static magnetization decreases. Our tight-binding Hubbard model with only on-site exchange leads to results very similar to those found by Griffin and Gumbs for a bounded electron gas model with an exchange interaction of finite range [lambda] if we take this to be equal to the lattice spacing.}, added-at = {2009-09-09T17:55:18.000+0200}, author = {Gumbs, G. and Griffin, A.}, biburl = {https://www.bibsonomy.org/bibtex/2201c2e0e548221dd7fe05fa2ca9a2f6e/pbuczek}, file = {Gumbs1980.pdf:Gumbs1980.pdf:PDF;Gumbs1980.pdf:Gumbs1980.pdf:PDF}, interhash = {879e151c9d028ce9fc5d768ae23036b3}, intrahash = {201c2e0e548221dd7fe05fa2ca9a2f6e}, journal = {Surface Science}, keywords = {imported}, month = {January}, number = {2-3}, owner = {pbuczek}, pages = {669--693}, timestamp = {2009-09-09T17:55:35.000+0200}, title = {Surface spin waves in a tight-binding itinerant-electron ferromagnet}, url = {http://www.sciencedirect.com/science/article/B6TVX-46SPP5F-42/2/ac4bf3e4cba69e376870f6b6653d4b71}, volume = 91, year = 1980 }