We report first-principles all-electron density-functional based studies of the electronic structure, magnetic ordering and anisotropy for the V15 molecular magnet. From these calculations, we determine a Heisenberg Hamiltonian with four antiferromagnetic and one {\em ferromagnetic} coupling. We perform direct diagonalization to determine the temperature dependence of the susceptibility. This Hamiltonian reproduces the experimentally observed spin S=1/2 ground state and low-lying S=3/2 excited state. A small anisotropy term is necessary to account for the temperature independent part of the magnetization curve.
@article{arxiv.cond-mat/0103031,
title = {The Hamiltonian of the V$_{15}$ Spin System from first-principles Density-Functional Calculations},
author = {Jens Kortus and C. Stephen Hellberg and Mark R. Pederson},
journal= {arXiv preprint arXiv:cond-mat/0103031},
year = {2009}
}
Comments
4 pages in RevTeX format + 2 ps-figures, accepted by PRL Feb. 2001 (previous version was an older version of the paper)