T. Herrmann et al., FERROMAGNETISM AND A TEMPERATURE-DRIVEN REORIENTATION TRANSITION IN THIN ITINERANT-ELECTRON FILMS, Physical review. B, Condensed matter, 58(2), 1998, pp. 831-839
The temperature-driven reorientation transition which, up to now; has
been studied by use of Heisenberg-type models only, is investigated wi
thin an itinerant-electron model. We consider the Hubbard model for a
thin fcc(100)film together with the dipole interaction and a layer-dep
endent anisotropy field. The isotropic part of the model is treated by
use of a generalization of the spectral:density approach to the film
geometry. The magnetic properties of the film are investigated as a fu
nction of temperature and film thickness and are analyzed in detail wi
th help of the spin- and layer-dependent quasiparticle density of stat
es. By calculating the temperature dependence of the second-order anis
otropy constants we find that both types of reorientation transitions,
from out-of-plane to in-plane (''Fe-type'') and from in-plane to out-
of-plane (''Ni-type'') magnetization are possible within our model. In
the latter case the inclusion of a positive volume anisotropy is vita
l. The reorientation transition is mediated by a strong reduction of t
he surface magnetization with respect to the inner layers as a functio
n of temperature and is found to depend significantly on the total ban
d occupation. [S0163-1829(98)03926-5].