We present detailed calculations of low-energy spin dynamics in the ``ferric wheel'' systems Na:Fe_6 and Cs:Fe_8 in a magnetic field. We compute by exact diagonalisation the low-energy spectra and matrix elements for total-spin and N'eel-vector components, and thus the time-dependent correlation functions of these operators. Comparison of our results with the semiclassical theory of coherent quantum tunnelling of the N'eel vector demonstrates the validity of a two-state description for the low-energy dynamics of ferric wheels. We discuss the implications of our results for mesoscopic quantum coherent phenomena, and for the experimental techniques to observe them, in molecular magnetic rings.
@article{arxiv.cond-mat/0109201,
title = {Spin dynamics and coherent tunnelling in the molecular magnetic rings Fe_6 and Fe_8},
author = {A. Honecker and F. Meier and Daniel Loss and B. Normand},
journal= {arXiv preprint arXiv:cond-mat/0109201},
year = {2009}
}
Comments
10 pages, 8 figures; considerably expanded discussion; to appear in Eur. Phys. J. B