We show that correlations established before quenching to very low temperatures, later drive the magnetization process of systems of single molecule magnets, after a magnetic field is applied at t=0. We also show that in SC lattices, m \propto sqrt(t), as observed in Fe_8, but only for 1+2*log_10(h_d/h_w) time decades, where h_d is a nearest neighbor dipolar magnetic field and a spin reversal can occur only if the field on it is within (-h_w,h_w). However, the sqrt(t) behavior is not universal. For BCC and FCC lattices, m \propto t^p, but p \simeq 0.7. The value to which m finally levels off is also given.
@article{arxiv.cond-mat/0309384,
title = {Magnetization Process of Single Molecule Magnets at Low Temperatures},
author = {J. F. Fernandez and J. J. Alonso},
journal= {arXiv preprint arXiv:cond-mat/0309384},
year = {2007}
}
Comments
5 LaTeX pages, 2 figures. Submitted to Phys. Rev. Lett. on 26 January 2003, accepted on 24 July 2003