In-plane dipole coupling anisotropy of a square ferromagnetic Heisenberg monolayer
Abstract
In this study we calculate the dipole-coupling-induced quartic in-plane anisotropy of a square ferromagnetic Heisenberg monolayer. This anisotropy increases with an increasing temperature, reaching its maximum value close to the Curie temperature of the system. At T=0 the system is isotropic, besides a small remaining anisotropy due to the zero-point motion of quantum mechanical spins. The reason for the dipole-coupling-induced anisotropy is the disturbance of the square spin lattice due to thermal fluctuations ('order-by-disorder' effect). For usual ferromagnets its strength is small as compared to other anisotropic contributions, and decreases by application of an external magnetic field. The results are obtained from a Heisenberg Hamiltonian by application of a mean field approach for a spin cluster, as well as from a many-body Green's function theory within the Tyablikov-decoupling (RPA).
Keywords
Cite
@article{arxiv.cond-mat/0208324,
title = {In-plane dipole coupling anisotropy of a square ferromagnetic Heisenberg monolayer},
author = {M. Dantziger and B. Glinsmann and S. Scheffler and B. Zimmermann and P. J. Jensen},
journal= {arXiv preprint arXiv:cond-mat/0208324},
year = {2009}
}
Comments
6 pages, 2 figures, accepted for publication in RPB