We investigate the bulk magnetic, electron paramagnetic resonance, and magneto-optical properties of {Ni4Mo12}, a magnetic molecule with antiferromagnetically coupled tetrahedral {Ni4Mo12} in a diamagnetic molybdenum matrix. The low-temperature magnetization exhibits steps at irregular field intervals, a result that cannot be explained using a Heisenberg model even if it is augmented by magnetic anisotropy and biquadratic terms. Allowing the exchange and anisotropy parameters to depend on the magnetic field provides the best fit to our data, suggesting that the molecular structure (and thus the interactions between spins) may be changing with applied magnetic field.
@article{arxiv.cond-mat/0509476,
title = {Observation of field-dependent magnetic parameters in the magnetic molecule {Ni4Mo12}},
author = {J. Schnack and M. Brueger and M. Luban and P. Koegerler and E. Morosan and R. Fuchs and R. Modler and Hiroyuki Nojiri and Ram C. Rai and Jinbo Cao and J. L. Musfeldt and Xing Wei},
journal= {arXiv preprint arXiv:cond-mat/0509476},
year = {2007}
}
Comments
10 pages, 12 figures, submitted to Phys. Rev. B. More information at http://www.physik.uni-osnabrueck.de/makrosysteme/